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= Socket Programming = | |||
* [http://beej.us/guide/bgnet/ Beej's Guide to Network Programming] | * [http://beej.us/guide/bgnet/ Beej's Guide to Network Programming] | ||
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* http://web.cecs.pdx.edu/~jrb/tcpip/lectures/pdfs/sockets.pdf | * http://web.cecs.pdx.edu/~jrb/tcpip/lectures/pdfs/sockets.pdf | ||
== Terms == | |||
There are two types of '''address domains'''. | There are two types of '''address domains'''. | ||
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* streaming server | * streaming server | ||
[https://www.makeuseof.com/what-are-tcp-and-udp-ports/ What Are TCP and UDP Ports?] | |||
* TCP | * TCP ports are used for services where you need '''secure and complete data transmission''' like emails, pictures, websites, etc. | ||
* | * UDP is more commonly used for quick lookups, and single use query-reply actions like video, voice, and game '''streaming'''. | ||
* Some common examples of TCP and UDP with their default ports: | * Some common examples of TCP and UDP with their default ports: | ||
** DNS lookup UDP 53 | ** DNS lookup UDP 53 | ||
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** Telnet TCP 23 | ** Telnet TCP 23 | ||
== General Idea == | |||
The steps involved in establishing a socket on the client side are as follows: | The steps involved in establishing a socket on the client side are as follows: | ||
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# Receive and send data by using '''read'''() and '''write'''(). | # Receive and send data by using '''read'''() and '''write'''(). | ||
== Internet Hearsay == | |||
* [http://www.ibm.com/developerworks/library/l-sockpit/ Tools for debugging sockets applications] using '''netstat''' and '''tcpdump''' GNU/Linux tools. | * [http://www.ibm.com/developerworks/library/l-sockpit/ Tools for debugging sockets applications] using '''netstat''' and '''tcpdump''' GNU/Linux tools. | ||
<pre> | <pre> | ||
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* [http://cboard.cprogramming.com/c-programming/136509-tcp-ip-server-client-programm-plusfiles.html bzero is deprecated. Use memset(foo, 0, size) instead] | * [http://cboard.cprogramming.com/c-programming/136509-tcp-ip-server-client-programm-plusfiles.html bzero is deprecated. Use memset(foo, 0, size) instead] | ||
== Make http request via telnet == | |||
* http://blog.tonycode.com/tech-stuff/http-notes/making-http-requests-via-telnet | * http://blog.tonycode.com/tech-stuff/http-notes/making-http-requests-via-telnet | ||
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</pre> | </pre> | ||
= Socket Programming Examples using C/C++/Qt = | |||
== Example 1 - Linux/Unix == | |||
http://www.linuxhowtos.org/C_C++/socket.htm. The codes are saved under [http://taichi.selfip.net:81/lang/c/socket/example1/ here]. | http://www.linuxhowtos.org/C_C++/socket.htm. The codes are saved under [http://taichi.selfip.net:81/lang/c/socket/example1/ here]. | ||
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* [http://stackoverflow.com/questions/7483301/how-do-i-print-client-address-while-running-server-code-in-socket Print client IP address] | * [http://stackoverflow.com/questions/7483301/how-do-i-print-client-address-while-running-server-code-in-socket Print client IP address] | ||
== Example 2 (in C) == | |||
http://www.prasannatech.net/2008/07/socket-programming-tutorial.html | http://www.prasannatech.net/2008/07/socket-programming-tutorial.html | ||
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</pre> | </pre> | ||
== Example 3 - Simple HTTP server == | |||
The example is modified (hear files only) from http://rosettacode.org/wiki/Hello_world/Web_server (This is a wonderful website which include creating hello world web server using different programming languages). PS. the instruction in http://mwaidyanatha.blogspot.com/2011/05/writing-simple-web-server-in-c.html is worth a look but 4 lines of creating HTML standard headlines is not successful and too complicated. | The example is modified (hear files only) from http://rosettacode.org/wiki/Hello_world/Web_server (This is a wonderful website which include creating hello world web server using different programming languages). PS. the instruction in http://mwaidyanatha.blogspot.com/2011/05/writing-simple-web-server-in-c.html is worth a look but 4 lines of creating HTML standard headlines is not successful and too complicated. | ||
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Compile and run it by ''gcc testServer.c; ./a.out''. | Compile and run it by ''gcc testServer.c; ./a.out''. | ||
== Example 4 - Mimic browser request == | |||
The code is based on the post. | The code is based on the post. | ||
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This is another similar post. http://www.binarytides.com/receive-full-data-with-recv-socket-function-in-c/ which teaches how to receive full data with recv socket function in C. | This is another similar post. http://www.binarytides.com/receive-full-data-with-recv-socket-function-in-c/ which teaches how to receive full data with recv socket function in C. | ||
=== Testing tcpclient.c === | |||
The result is a program that connects to google and downloads (the first 1000 bytes of) the google homepage. | The result is a program that connects to google and downloads (the first 1000 bytes of) the google homepage. | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
=== Testing tcpserver.c and tcpclient2.c === | |||
Server side: | Server side: | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
== Example 5 - Windows socket (almost implies C++) == | |||
* http://www.tenouk.com/cnwinsock2tutorials.html | * http://www.tenouk.com/cnwinsock2tutorials.html | ||
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* http://www.codeproject.com/Articles/412511/Simple-client-server-network-using-Cplusplus-and-W | * http://www.codeproject.com/Articles/412511/Simple-client-server-network-using-Cplusplus-and-W | ||
== Example 6 Get image using Qt == | |||
See Chapter 14. Foundation of Qt Development. The code is on https://github.com/arraytools/Qt/tree/master/FQD/Chapter14. | See Chapter 14. Foundation of Qt Development. The code is on https://github.com/arraytools/Qt/tree/master/FQD/Chapter14. | ||
== Example 7 Trip planner using Qt == | |||
See Chapter 15. Networking on C++ GUI Programming Qt 4. The code is on http://taichi.selfip.net:81/lang/c/qt-book/chap15/. | See Chapter 15. Networking on C++ GUI Programming Qt 4. The code is on http://taichi.selfip.net:81/lang/c/qt-book/chap15/. | ||
= Basic(s) = | |||
== C++ standard == | |||
* https://isocpp.org/ [https://isocpp.org/std/status Status], [https://isocpp.org/std/the-standard Current Standard], Articles, Events & Training. | * https://isocpp.org/ [https://isocpp.org/std/status Status], [https://isocpp.org/std/the-standard Current Standard], Articles, Events & Training. | ||
* [https://en.wikipedia.org/wiki/C%2B%2B C++ Wikipedia] | * [https://en.wikipedia.org/wiki/C%2B%2B C++ Wikipedia] | ||
== Cheat sheet, Tutorial, Crash course == | |||
* [https://www.youtube.com/watch?v=2egL4y_VpYg What – if anything – have we learned from C++?] by Bjarne Stroustrup. | * [https://www.youtube.com/watch?v=2egL4y_VpYg What – if anything – have we learned from C++?] by Bjarne Stroustrup. | ||
* https://github.com/jameshfisher/cc-cheatsheet The cheat sheet is created using LibreOffice Write (odt format) and it fits a A4 paper. | * https://github.com/jameshfisher/cc-cheatsheet The cheat sheet is created using LibreOffice Write (odt format) and it fits a A4 paper. | ||
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* [http://en.opensuse.org/images/b/b9/C---for-C-programmers.pdf C++ for C programmers] | * [http://en.opensuse.org/images/b/b9/C---for-C-programmers.pdf C++ for C programmers] | ||
* [http://www.loria.fr/~rougier/teaching/c++-crash-course/index.html C++ crash course for C programmers] | * [http://www.loria.fr/~rougier/teaching/c++-crash-course/index.html C++ crash course for C programmers] | ||
* [ | * [https://www.stat.berkeley.edu/~scf/paciorek-cppWorkshop.pdf C++ for Statisticians] with a focus on interfacing from R and R packages. | ||
* [http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list The Definitive C++ Book Guide and List] | * [http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list The Definitive C++ Book Guide and List] | ||
* [http://mathbits.com/MathBits/CompSci/compsci.htm Introduction to Programming in C++] which is suitable for high school classes. | * [http://mathbits.com/MathBits/CompSci/compsci.htm Introduction to Programming in C++] which is suitable for high school classes. | ||
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* http://www.makeuseof.com/tag/best-youtube-programming-tutorials/ The 17 Best YouTube Programming Tutorials (including C++) | * http://www.makeuseof.com/tag/best-youtube-programming-tutorials/ The 17 Best YouTube Programming Tutorials (including C++) | ||
* https://blog.tartanllama.xyz/ | * https://blog.tartanllama.xyz/ | ||
* [http://www.langmead-lab.org/teaching-materials/#intermediate Teaching Materials] by Ben Langmead | |||
== Differences between C and C++ == | |||
* http://cs-fundamentals.com/tech-interview/c/difference-between-c-and-cpp.php | * http://cs-fundamentals.com/tech-interview/c/difference-between-c-and-cpp.php | ||
* http://techwelkin.com/difference-between-c-and-c-plus-plus | * http://techwelkin.com/difference-between-c-and-c-plus-plus | ||
* https://www.invensis.net/blog/it/25-key-differencesbetween-c-plus-plus/ | * https://www.invensis.net/blog/it/25-key-differencesbetween-c-plus-plus/ | ||
== Books for C++ == | |||
[http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list The Definitive C++ Book Guide and List] from the stackoverflow post. | [http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list The Definitive C++ Book Guide and List] from the stackoverflow post. | ||
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* [http://www.amazon.com/gp/bestsellers/books/9045760011/ref=sr_bs_1 Best sellers on C++] from Amazon. | * [http://www.amazon.com/gp/bestsellers/books/9045760011/ref=sr_bs_1 Best sellers on C++] from Amazon. | ||
== Books for C == | |||
* [https://www.hpe.com/us/en/insights/articles/top-linux-developers-recommended-programming-books-1808.html Top Linux developers' recommended programming books] | * [https://www.hpe.com/us/en/insights/articles/top-linux-developers-recommended-programming-books-1808.html Top Linux developers' recommended programming books] | ||
* [http://www.ossblog.org/master-c-programming-with-open-source-books/ MASTER C++ PROGRAMMING WITH OPEN-SOURCE BOOKS] | * [http://www.ossblog.org/master-c-programming-with-open-source-books/ MASTER C++ PROGRAMMING WITH OPEN-SOURCE BOOKS] | ||
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* Kenneth Reek (1998) [https://www.cs.rit.edu/~kar/pointers.on.c/ Pointers on C] | * Kenneth Reek (1998) [https://www.cs.rit.edu/~kar/pointers.on.c/ Pointers on C] | ||
== C++11 for Ubuntu 12.04 == | |||
http://askubuntu.com/questions/113291/how-do-i-install-gcc-4-7 | http://askubuntu.com/questions/113291/how-do-i-install-gcc-4-7 | ||
<pre> | <pre> | ||
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When issuing the last command, it will ask what version of gcc to use. | When issuing the last command, it will ask what version of gcc to use. | ||
== First code == | |||
=== The simplest c/c++ code === | |||
Mentioned by the above book ''Exploring Beaglebone: Tools and Techniques for Building with Embedded Linux''. | Mentioned by the above book ''Exploring Beaglebone: Tools and Techniques for Building with Embedded Linux''. | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
=== Hello World === | |||
C version (compiled by gcc helloworld.c) | C version (compiled by gcc helloworld.c) | ||
<pre> | <pre> | ||
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Running '''g++ helloworld.cpp''' actually involved several steps (process cpp to another cpp, created assembly code, compile assembly code, link and create an executable). See the book ''Exploring Beaglebone: Tools and Techniques for Building with Embedded Linux'' Chapter 2.3. | Running '''g++ helloworld.cpp''' actually involved several steps (process cpp to another cpp, created assembly code, compile assembly code, link and create an executable). See the book ''Exploring Beaglebone: Tools and Techniques for Building with Embedded Linux'' Chapter 2.3. | ||
=== #include <iostream> === | |||
* http://stackoverflow.com/questions/26086842/why-should-i-include-the-header-file-iostream-after-using-the-namespace-std | * http://stackoverflow.com/questions/26086842/why-should-i-include-the-header-file-iostream-after-using-the-namespace-std | ||
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</pre> | </pre> | ||
=== namespace === | |||
* http://www.cplusplus.com/doc/tutorial/namespaces/ | * http://www.cplusplus.com/doc/tutorial/namespaces/ | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== The std namespace --- C++ Standard Library === | |||
https://en.wikipedia.org/wiki/C%2B%2B_Standard_Library | https://en.wikipedia.org/wiki/C%2B%2B_Standard_Library | ||
* The C++ Standard Library is a collection of classes and functions. | * The C++ Standard Library is a collection of classes and functions. | ||
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# C standard library | # C standard library | ||
=== int main() return value === | |||
* http://stackoverflow.com/questions/204476/what-should-main-return-in-c-and-c | * http://stackoverflow.com/questions/204476/what-should-main-return-in-c-and-c | ||
* http://stackoverflow.com/questions/13205941/whats-the-meaning-of-the-return-value-of-int-main-and-how-to-display-it | * http://stackoverflow.com/questions/13205941/whats-the-meaning-of-the-return-value-of-int-main-and-how-to-display-it | ||
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The return value for main should indicate how the program exited. Normal exit is generally represented by a 0 return value from main. Abnormal termination is usually signalled by a non-zero return but there is no standard for how non-zero codes are interpreted. | The return value for main should indicate how the program exited. Normal exit is generally represented by a 0 return value from main. Abnormal termination is usually signalled by a non-zero return but there is no standard for how non-zero codes are interpreted. | ||
=== Naming convension | == Main function == | ||
[https://opensource.com/article/19/5/how-write-good-c-main-function How to write a good C main function] | |||
== Naming convension == | |||
* https://google.github.io/styleguide/cppguide.html | * https://google.github.io/styleguide/cppguide.html | ||
* For private data members, prefixed with '''m_''' (eg. see [http://www.themagpi.com/issue/issue-23/ TheMagPi-issue 23]). | * For private data members, prefixed with '''m_''' (eg. see [http://www.themagpi.com/issue/issue-23/ TheMagPi-issue 23]). | ||
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** For example, the [https://sourceforge.net/projects/qroundprogressbar/ QRoundProgressBar] (Qt Circular Progress Bar Widget). | ** For example, the [https://sourceforge.net/projects/qroundprogressbar/ QRoundProgressBar] (Qt Circular Progress Bar Widget). | ||
== Some Words about Standalone Application vs Web Application == | |||
* Users can make use of the hardware power on my own machine | * Users can make use of the hardware power on my own machine | ||
* Users don't worry his/her data will be used by 3rd party | * Users don't worry his/her data will be used by 3rd party | ||
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* Maintainer don't need to worry the server can be hacked (purposely or incidentally). The server has to pass some security exam before it can be opened to public. | * Maintainer don't need to worry the server can be hacked (purposely or incidentally). The server has to pass some security exam before it can be opened to public. | ||
== Header/Include guard, Preprocessor == | |||
'''#ifndef ... #define ... #endif'''. See [http://en.wikipedia.org/wiki/Include_guard wikipedia] and [http://www.cplusplus.com/doc/tutorial/preprocessor/ cplusplus.com]. | '''#ifndef ... #define ... #endif'''. See [http://en.wikipedia.org/wiki/Include_guard wikipedia] and [http://www.cplusplus.com/doc/tutorial/preprocessor/ cplusplus.com]. | ||
== Basic Arithmetic == | |||
<pre> | <pre> | ||
double a = 10, b=3; | double a = 10, b=3; | ||
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</pre> | </pre> | ||
== bool type == | |||
* http://en.cppreference.com/w/cpp/language/types (true and false) | * http://en.cppreference.com/w/cpp/language/types (true and false) | ||
* [http://www.cplusplus.com/forum/beginner/71562/ true vs TRUE] and false vs FALSE | * [http://www.cplusplus.com/forum/beginner/71562/ true vs TRUE] and false vs FALSE | ||
== Data Type Ranges == | |||
* http://msdn.microsoft.com/en-us/library/s3f49ktz(v=vs.90).aspx | * http://msdn.microsoft.com/en-us/library/s3f49ktz(v=vs.90).aspx | ||
{| class="wikitable" | {| class="wikitable" | ||
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* http://www.cplusplus.com/doc/tutorial/variables/ | * http://www.cplusplus.com/doc/tutorial/variables/ | ||
== Conditional operation ? : == | |||
* https://msdn.microsoft.com/en-us/library/exefbdtf.aspx | * https://msdn.microsoft.com/en-us/library/exefbdtf.aspx | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== Increment ++ operator == | |||
Note that ++variable is slightly faster than its alternative variable++ since the alternative needs to make a copy of itself before returning the result. (see SeqAn tutorial [http://seqan.readthedocs.org/en/master/Tutorial/FirstStepsInSeqAn.html#tutorial-first-steps-in-seqan here]) | Note that ++variable is slightly faster than its alternative variable++ since the alternative needs to make a copy of itself before returning the result. (see SeqAn tutorial [http://seqan.readthedocs.org/en/master/Tutorial/FirstStepsInSeqAn.html#tutorial-first-steps-in-seqan here]) | ||
== namespace == | |||
=== Create Utilities Function === | |||
Don't put them in a class; just make them non-member functions at namespace scope. | Don't put them in a class; just make them non-member functions at namespace scope. | ||
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</source> | </source> | ||
== Memory Management == | |||
* An Introduction to '''Pointers''' for Programmers http://www.makeuseof.com/tag/introduction-pointers-programmers/ | * An Introduction to '''Pointers''' for Programmers http://www.makeuseof.com/tag/introduction-pointers-programmers/ | ||
* [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-096-introduction-to-c-january-iap-2011/lecture-notes/ MIP Open Course] | * [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-096-introduction-to-c-january-iap-2011/lecture-notes/ MIP Open Course] | ||
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As mentioned in the [http://www.stroustrup.com/bs_faq2.html Stroustrup C++ Style and Technique FAQ]. ''A vector keeps track of the memory it uses to store its elements. When a vector needs more memory for elements, it allocates more; when a vector goes out of scope, it frees that memory. Therefore, the user need not be concerned with the allocation and deallocation of memory for vector elements.'' | As mentioned in the [http://www.stroustrup.com/bs_faq2.html Stroustrup C++ Style and Technique FAQ]. ''A vector keeps track of the memory it uses to store its elements. When a vector needs more memory for elements, it allocates more; when a vector goes out of scope, it frees that memory. Therefore, the user need not be concerned with the allocation and deallocation of memory for vector elements.'' | ||
=== Heap vs Stack === | |||
When an object is needed within several different functions calls, it might be helpful to create it on the heap instead. | When an object is needed within several different functions calls, it might be helpful to create it on the heap instead. | ||
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# C++ Primer Plus Chapter 9. | # C++ Primer Plus Chapter 9. | ||
=== The '''auto_ptr''' Class (deprecated as of C++11) === | |||
* See Chapter 16 of C++ Primer Plus. | * See Chapter 16 of C++ Primer Plus. | ||
* http://www.cplusplus.com/reference/memory/auto_ptr/. This class template is deprecated as of C++11. unique_ptr is a new facility with a similar functionality, but with improved security (no fake copy assignments), added features (deleters) and support for arrays. | * http://www.cplusplus.com/reference/memory/auto_ptr/. This class template is deprecated as of C++11. unique_ptr is a new facility with a similar functionality, but with improved security (no fake copy assignments), added features (deleters) and support for arrays. | ||
== new, delete operators, pointers and dynamic memory == | |||
Use new/delete instead of malloc()/free() which depends on <cstdlib> in C++. For example, the following code was a modification from Listing 4.22 (p169) <delete.cpp> from the book 'C++ Primer Plus'. | Use new/delete instead of malloc()/free() which depends on <cstdlib> in C++. For example, the following code was a modification from Listing 4.22 (p169) <delete.cpp> from the book 'C++ Primer Plus'. | ||
The memory created by new operator is called '''heap''' or '''free store'''. Forgetting to use '''delete''' operator will cause a memory leak. This kind of storage is called '''dynamic storage''' which differs from '''automatic storage''' and '''static storage/stack'''. | The memory created by new operator is called '''heap''' or '''free store'''. Forgetting to use '''delete''' operator will cause a memory leak. This kind of storage is called '''dynamic storage''' which differs from '''automatic storage''' and '''static storage/stack'''. | ||
< | <syntaxhighlight lang='cpp'> | ||
#include <iostream> | #include <iostream> | ||
#include <cstring> // strlen() | #include <cstring> // strlen() | ||
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return 0; | return 0; | ||
} | } | ||
</ | </syntaxhighlight> | ||
* '''new''' allows to allocate a variable length arrays while allocating arrays on the stack stack size must be constant. See p52 of [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-096-introduction-to-c-january-iap-2011/lecture-notes/ MIT Open Course] or p33 of [http://www.themagpi.com/issue/issue-23/ TheMagPi issue 23]. | * '''new''' allows to allocate a variable length arrays while allocating arrays on the stack stack size must be constant. See p52 of [http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-096-introduction-to-c-january-iap-2011/lecture-notes/ MIT Open Course] or p33 of [http://www.themagpi.com/issue/issue-23/ TheMagPi issue 23]. | ||
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* When a program interacts with other programs in a GUI or network environment, it typically passes or receives pointers to objects. | * When a program interacts with other programs in a GUI or network environment, it typically passes or receives pointers to objects. | ||
=== scalar === | |||
<pre> | <pre> | ||
int *pn = new int; // dynamic | int *pn = new int; // dynamic | ||
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</pre> | </pre> | ||
=== Array === | |||
* [https://www.howtoforge.com/linux-c-programming-tutorial-part-19-pointers-and-arrays/ Linux C Programming Tutorial Part 19: Pointers and Arrays] from HowToForge. | |||
* Every array contains a sequence of one or more objects of the same type. The number of elements in the array must be known at compile time, which requirement implies that arrays cannot grow or shrink dynamically the way library containers do. See 10.1.3 of Accelerated C++. | * Every array contains a sequence of one or more objects of the same type. The number of elements in the array must be known at compile time, which requirement implies that arrays cannot grow or shrink dynamically the way library containers do. See 10.1.3 of Accelerated C++. | ||
* Because arrays are not class types, they have no members. In particular, they do not have the ''size_type'' member to name an appropriate type to deal with the size of an array. | * Because arrays are not class types, they have no members. In particular, they do not have the ''size_type'' member to name an appropriate type to deal with the size of an array. | ||
* The <cstddef> header defines '''size_t''', which is a more general type. | * The <cstddef> header defines '''size_t''', which is a more general type. <syntaxhighlight lang='cpp'> | ||
<syntaxhighlight lang='cpp'> | |||
const size_t NDim = 3; | const size_t NDim = 3; | ||
double coords[NDim]; | double coords[NDim]; | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
* There is a fundamental relationship between arrays and pointers. | * There is a fundamental relationship between arrays and pointers. <syntaxhighlight lang='cpp'> | ||
<syntaxhighlight lang='cpp'> | |||
*coords = 1.5; // the array's initial element | *coords = 1.5; // the array's initial element | ||
</syntaxhighlight> | </syntaxhighlight> | ||
<syntaxhighlight lang='cpp'> | : <syntaxhighlight lang='cpp'> | ||
int *pn = new int[10]; // OR int *pn; pn = new int[10]; | int *pn = new int[10]; // OR int *pn; pn = new int[10]; | ||
pn[1] =3; | pn[1] =3; | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== function === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
# Listing 4.22.1 <delete.cpp> from C++ Prime Plus (5th ed) | # Listing 4.22.1 <delete.cpp> from C++ Prime Plus (5th ed) | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== use new(delete) in a class constructor(destructor) === | |||
< | <syntaxhighlight lang='cpp'> | ||
# Listing 12.4, 12.5 and p591-593 of C++ Primer Plus (5th ed) | # Listing 12.4, 12.5 and p591-593 of C++ Primer Plus (5th ed) | ||
String::String (const String & st) | String::String (const String & st) | ||
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delete [] str; | delete [] str; | ||
} | } | ||
</ | </syntaxhighlight> | ||
=== dereference === | |||
< | <syntaxhighlight lang='cpp'> | ||
Fraction *pFrac = new Fraction(1, 2); | Fraction *pFrac = new Fraction(1, 2); | ||
(*pFrac).get_num(); // OR pFrac->get_num(); | (*pFrac).get_num(); // OR pFrac->get_num(); | ||
(*pFrac).member; // pFrac->member; | (*pFrac).member; // pFrac->member; | ||
</ | </syntaxhighlight> | ||
=== combining dereference and increment in a single expression === | |||
< | <syntaxhighlight lang='cpp'> | ||
auto pbeg = v.begin(); | auto pbeg = v.begin(); | ||
// print elements up to the first negative value | // print elements up to the first negative value | ||
while (pbeg != v.end() && *pbeg >= 0) | while (pbeg != v.end() && *pbeg >= 0) | ||
cout << *pbeg++ << endl; // print the current value and advance pbeg | cout << *pbeg++ << endl; // print the current value and advance pbeg | ||
</ | </syntaxhighlight> | ||
<span style="color: red"> The precedence of postfix increment is higher than that of the dereference operator, so *pbeg++ is equivalent to *(pbeg++) </span>. The operand of * is the unincremented value of pbeg. Thus, the statement prints the element to which pbeg originally pointed and increments pbeg. | <span style="color: red"> The precedence of postfix increment is higher than that of the dereference operator, so *pbeg++ is equivalent to *(pbeg++) </span>. The operand of * is the unincremented value of pbeg. Thus, the statement prints the element to which pbeg originally pointed and increments pbeg. | ||
=== variable array size in new === | |||
< | <syntaxhighlight lang='cpp'> | ||
int n; | int n; | ||
cout << "How many elements?"; | cout << "How many elements?"; | ||
Line 915: | Line 917: | ||
.... | .... | ||
delete [] p; | delete [] p; | ||
</ | </syntaxhighlight> | ||
=== null pointer === | |||
See [http://c-faq.com/null/index.html Null Pointers] in comp.lang.c Frequently Asked Questions. | See [http://c-faq.com/null/index.html Null Pointers] in comp.lang.c Frequently Asked Questions. | ||
There are several ways to create a null pointer. | There are several ways to create a null pointer. | ||
< | <syntaxhighlight lang='cpp'> | ||
int *p1 = nullptr; // C++11 | int *p1 = nullptr; // C++11 | ||
int *p2 = 0; | int *p2 = 0; | ||
int *p3 = NULL; // must #include cstdlib header which defines the preprocessor variable NULL as 0. | int *p3 = NULL; // must #include cstdlib header which defines the preprocessor variable NULL as 0. | ||
</ | </syntaxhighlight> | ||
Modern C++ programs generally should avoid using NULL and use nullptr instead. | Modern C++ programs generally should avoid using NULL and use nullptr instead. | ||
Line 937: | Line 939: | ||
</pre> | </pre> | ||
=== dealing with problems with memory allocation === | |||
If the memory requested is not available, the new operator returns a null pointer. | If the memory requested is not available, the new operator returns a null pointer. | ||
You can test for this possibility and take the appropriate action. | You can test for this possibility and take the appropriate action. | ||
< | <syntaxhighlight lang='cpp'> | ||
int *p = new int[1000]; | int *p = new int[1000]; | ||
if (!p) { | if (!p) { | ||
Line 947: | Line 949: | ||
exit(-1); | exit(-1); | ||
} | } | ||
</ | </syntaxhighlight> | ||
=== Memory leak === | |||
[http://stackoverflow.com/questions/9979776/does-calling-new-twice-on-the-same-pointer-without-calling-delete-in-betwe Does calling '''new''' operator twice on the same pointer without calling '''delete''' operator in between cause a memory leak?] | [http://stackoverflow.com/questions/9979776/does-calling-new-twice-on-the-same-pointer-without-calling-delete-in-betwe Does calling '''new''' operator twice on the same pointer without calling '''delete''' operator in between cause a memory leak?] | ||
The answer is Yes. | The answer is Yes. | ||
=== Test memory leak === | |||
The following C++ code was used to test a memory leak and also the capacity of memory. Note that when 'n' is declared as unsigned int, the maximum value can be 4,294,967,295=2^32-1 which corresponds to 32,767 MB (about 32 GB) in size for a double vector (assume 8 bytes). If I change the type of n to "unsigned long long", its range can go up to 18,446,744,073,709,551,615=2^64-1 or 137438953472 GB in size for a double vector. | The following C++ code was used to test a memory leak and also the capacity of memory. Note that when 'n' is declared as unsigned int, the maximum value can be 4,294,967,295=2^32-1 which corresponds to 32,767 MB (about 32 GB) in size for a double vector (assume 8 bytes). If I change the type of n to "unsigned long long", its range can go up to 18,446,744,073,709,551,615=2^64-1 or 137438953472 GB in size for a double vector. | ||
Note that the program should be built in x64 instead of win32 version in Visual Studio if we like to test it on non-Windows-XP OS on Windows. Linux OS does not need to worry... | Note that the program should be built in x64 instead of win32 version in Visual Studio if we like to test it on non-Windows-XP OS on Windows. Linux OS does not need to worry... | ||
< | <syntaxhighlight lang='cpp'> | ||
#include <iostream> | #include <iostream> | ||
Line 1,010: | Line 1,012: | ||
return 0; | return 0; | ||
} | } | ||
</ | </syntaxhighlight> | ||
and my testing result on Windows XP with 2GB physical memory & 2GB virtual memory. The program is compiled into 32-bit console application. It is a different story when tested on 64-bit Windows 7. | and my testing result on Windows XP with 2GB physical memory & 2GB virtual memory. The program is compiled into 32-bit console application. It is a different story when tested on 64-bit Windows 7. | ||
{| class="wikitable sortable collapsible" border="1" style="border-collapse:collapse; text-align:center;" | {| class="wikitable sortable collapsible" border="1" style="border-collapse:collapse; text-align:center;" | ||
Line 1,029: | Line 1,031: | ||
|} | |} | ||
== Enumerations == | |||
See 2.3.3 of The C++ Programming language or http://en.cppreference.com/w/cpp/language/enum | See 2.3.3 of The C++ Programming language or http://en.cppreference.com/w/cpp/language/enum | ||
=== Unscoped enumeration === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
enum Color { RED, GREEN, BLUE }; | enum Color { RED, GREEN, BLUE }; | ||
Line 1,044: | Line 1,046: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Scoped enumerations === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
enum class Color { RED, GREEN = 20, BLUE }; | enum class Color { RED, GREEN = 20, BLUE }; | ||
Line 1,058: | Line 1,060: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== this keyword/pointer == | |||
The '''this''' keyword is valid only inside a member function, where it denotes a pointer to the object on which the member function is operating. For example, inside Vec::operator=, the type of this is Vec*, because this is a pointer to the Vec object of which operator= is a member. For a binary operator, such as assignment, this is bound to the left-hand operand. Ordinarily, this is used when we need to refer to the object itself, as we do here both in the initial if test and in the return. | The '''this''' keyword is valid only inside a member function, where it denotes a pointer to the object on which the member function is operating. For example, inside Vec::operator=, the type of this is Vec*, because this is a pointer to the Vec object of which operator= is a member. For a binary operator, such as assignment, this is bound to the left-hand operand. Ordinarily, this is used when we need to refer to the object itself, as we do here both in the initial if test and in the return. | ||
* http://en.cppreference.com/w/cpp/language/this | * http://en.cppreference.com/w/cpp/language/this | ||
== Communication between objects == | |||
See Pi magazine [http://www.themagpi.com/issue/issue-24/ issue 24]. The secret is to use '''this''' pointer to pass a pointer to the data member object. | See Pi magazine [http://www.themagpi.com/issue/issue-24/ issue 24]. The secret is to use '''this''' pointer to pass a pointer to the data member object. | ||
In header files, | In header files, | ||
Line 1,105: | Line 1,107: | ||
</pre> | </pre> | ||
== C++ videos == | |||
* (73) http://thenewboston.org/list.php?cat=16 | * (73) http://thenewboston.org/list.php?cat=16 | ||
* (54) videos http://xoax.net/cpp/crs/console/index.php | * (54) videos http://xoax.net/cpp/crs/console/index.php | ||
== Type casting == | |||
by declaiming explicitly like (float)5 or using suffix like 5f. | by declaiming explicitly like (float)5 or using suffix like 5f. | ||
== Global variables, header == | |||
http://stackoverflow.com/questions/9702053/how-to-declare-a-global-variable-in-c | http://stackoverflow.com/questions/9702053/how-to-declare-a-global-variable-in-c | ||
Line 1,130: | Line 1,132: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== C vs C++ with functions == | |||
In non-object programming, we use | In non-object programming, we use | ||
<pre> | <pre> | ||
Line 1,141: | Line 1,143: | ||
</pre> | </pre> | ||
== <cstdlib> vs <stdlib.h> == | |||
The first one is for C++ and the other is for C. See [http://stackoverflow.com/questions/2900785/whats-the-difference-between-cstdlib-and-stdlib-h here]. | The first one is for C++ and the other is for C. See [http://stackoverflow.com/questions/2900785/whats-the-difference-between-cstdlib-and-stdlib-h here]. | ||
== Function Prototypes == | |||
For example, | For example, | ||
<pre> | <pre> | ||
Line 1,156: | Line 1,158: | ||
Functon prototyping is often hidden in the '''include''' files. | Functon prototyping is often hidden in the '''include''' files. | ||
== Pass function name in a function == | |||
See | See | ||
* Chapter 4 of Accelerated C++. [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter04/Student_info.cc <Student_info.cc>]. Well there is no functions as arguments in this case. Just want to show an opposite of write_analysis() function. | * Chapter 4 of Accelerated C++. [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter04/Student_info.cc <Student_info.cc>]. Well there is no functions as arguments in this case. Just want to show an opposite of write_analysis() function. | ||
Line 1,202: | Line 1,204: | ||
For the '''ostream &''' parameter, see [[#Write_a_Function_to_Contain_an_Argument_of_Output_Device_.28eg_file.2C_screen.29|Write a Function to Contain an Argument of Output Device]]. | For the '''ostream &''' parameter, see [[#Write_a_Function_to_Contain_an_Argument_of_Output_Device_.28eg_file.2C_screen.29|Write a Function to Contain an Argument of Output Device]]. | ||
== Argument Passing in Functions == | |||
References as a function argument seems more popular for numerical values and Pointers as a function argument seems popular for char arrays. It is introduced in C++ Primer Chapter 6.2.2. | References as a function argument seems more popular for numerical values and Pointers as a function argument seems popular for char arrays. It is introduced in C++ Primer Chapter 6.2.2. | ||
The argument can be a scalar or an array. Also it be numerical values or character strings. | The argument can be a scalar or an array. Also it be numerical values or character strings. | ||
=== Pointers as a function argument === | |||
The following example is coming from http://www.nongnu.org/c-prog-book/online/x641.html. See also [http://www.cplusplus.com/doc/tutorial/pointers/ cplusplus.com] tutorial about pointers. | The following example is coming from http://www.nongnu.org/c-prog-book/online/x641.html. See also [http://www.cplusplus.com/doc/tutorial/pointers/ cplusplus.com] tutorial about pointers. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 1,257: | Line 1,259: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== '''References as a function argument''' === | |||
The new variable is called '''Reference Variables''' which is a name that acts as an '''alias'''. This is described in C++ Primer Plus Chapter 8. See also | The new variable is called '''Reference Variables''' which is a name that acts as an '''alias'''. This is described in C++ Primer Plus Chapter 8. See also | ||
* [http://www.tutorialspoint.com/cplusplus/cpp_references.htm tutorialspoint.com] | * [http://www.tutorialspoint.com/cplusplus/cpp_references.htm tutorialspoint.com] | ||
Line 1,363: | Line 1,365: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Comparison of Reference and Pointer === | |||
{| class="wikitable sortable collapsible" border="1" style="border-collapse:collapse; text-align:center;" | {| class="wikitable sortable collapsible" border="1" style="border-collapse:collapse; text-align:center;" | ||
|- | |- | ||
Line 1,397: | Line 1,399: | ||
|} | |} | ||
== lvalue and rvalue == | |||
* Chapter 8.5.6 Pass-vy-value vs pass-by-reference of PPP (an easy to follow book with essential concepts there). | * Chapter 8.5.6 Pass-vy-value vs pass-by-reference of PPP (an easy to follow book with essential concepts there). | ||
* Chapter 6.4 Objects and Values of The C++ Programming Language. | * Chapter 6.4 Objects and Values of The C++ Programming Language. | ||
Line 1,420: | Line 1,422: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== rvalue reference, && and Move semantics == | |||
This is used to avoid 'copy' data. The situation happened in copy constructor or assignment. It is important especially for large data. | This is used to avoid 'copy' data. The situation happened in copy constructor or assignment. It is important especially for large data. | ||
Line 1,426: | Line 1,428: | ||
* Google it. | * Google it. | ||
== Pass the (address) of the pointer (char array) as function argument == | |||
http://stackoverflow.com/questions/1217173/how-to-have-a-char-pointer-as-an-out-parameter-for-c-function. | http://stackoverflow.com/questions/1217173/how-to-have-a-char-pointer-as-an-out-parameter-for-c-function. | ||
Line 1,470: | Line 1,472: | ||
</pre> | </pre> | ||
== Function and Arrays == | |||
(C++ Primer Ch 6.2.4 Array Parameters) Because arrays are passed as pointers, functions ordinarily don't know the size of the array they are given. There are three techniques used to manage pointer parameters | (C++ Primer Ch 6.2.4 Array Parameters) Because arrays are passed as pointers, functions ordinarily don't know the size of the array they are given. There are three techniques used to manage pointer parameters | ||
# using a marker to specify the extent of a character array (null character for C-style strings) | # using a marker to specify the extent of a character array (null character for C-style strings) | ||
Line 1,509: | Line 1,511: | ||
</pre> | </pre> | ||
=== Pointer and const === | |||
See Chapter 7 of C++ Primer Plus (5th ed). | See Chapter 7 of C++ Primer Plus (5th ed). | ||
<pre> | <pre> | ||
Line 1,520: | Line 1,522: | ||
</pre> | </pre> | ||
=== Functions and Two-Dimensional Arrays === | |||
<pre> | <pre> | ||
int data[3][4] = {{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}; | int data[3][4] = {{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}; | ||
Line 1,549: | Line 1,551: | ||
</pre> | </pre> | ||
=== command line arguments, arguments to main === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
int main(int argc, char *argv[]) { ... } // argv is an array of pointers to C-style character strings. | int main(int argc, char *argv[]) { ... } // argv is an array of pointers to C-style character strings. | ||
Line 1,561: | Line 1,563: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Varying parameters === | |||
(C++11) '''initializer_list''' parameters. | (C++11) '''initializer_list''' parameters. | ||
<pre> | <pre> | ||
Line 1,578: | Line 1,580: | ||
</pre> | </pre> | ||
=== Ellipsis parameters === | |||
Ellipsis parameters are in C++ to allow programs to interface to C code that uses a C library facility named '''varargs'''. | Ellipsis parameters are in C++ to allow programs to interface to C code that uses a C library facility named '''varargs'''. | ||
<pre> | <pre> | ||
Line 1,585: | Line 1,587: | ||
</pre> | </pre> | ||
=== Return a pointer to an array === | |||
See C++ Primer Ch 6.3.3. | See C++ Primer Ch 6.3.3. | ||
Line 1,608: | Line 1,610: | ||
</pre> | </pre> | ||
=== Pointer, vector and element === | |||
* See PPP 20.1 (Storing and processing data) and 20.1.1 (Working with data). | * See PPP 20.1 (Storing and processing data) and 20.1.1 (Working with data). | ||
<pre> | <pre> | ||
Line 1,624: | Line 1,626: | ||
</pre> | </pre> | ||
=== pass a vector of strings using reference === | |||
See how to pass a vector of strings using reference. | See how to pass a vector of strings using reference. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 1,760: | Line 1,762: | ||
For 2 dimensional matrix of string, see [[#2_dimensional_matrix|the example below]]. | For 2 dimensional matrix of string, see [[#2_dimensional_matrix|the example below]]. | ||
== Container class in C++ vs simple array in C == | |||
https://isocpp.org/wiki/faq/containers | https://isocpp.org/wiki/faq/containers | ||
== try { ... } catch { ... } for exception handling == | |||
* http://msdn.microsoft.com/en-us/library/6dekhbbc(v=vs.80).aspx | * http://msdn.microsoft.com/en-us/library/6dekhbbc(v=vs.80).aspx | ||
* http://www.cplusplus.com/doc/tutorial/exceptions/ | * http://www.cplusplus.com/doc/tutorial/exceptions/ | ||
Line 1,877: | Line 1,879: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Exception classes === | |||
http://www.cplusplus.com/reference/exception/exception/ | http://www.cplusplus.com/reference/exception/exception/ | ||
* logic_error | * logic_error | ||
Line 1,889: | Line 1,891: | ||
* underflow_error | * underflow_error | ||
== '''Class''' == | |||
The fundamental ideas behind classes are '''data abstraction''' and '''encapsulation'''. | The fundamental ideas behind classes are '''data abstraction''' and '''encapsulation'''. | ||
Line 1,896: | Line 1,898: | ||
Encapsulation enforces the separation of a class' interface and implementation. | Encapsulation enforces the separation of a class' interface and implementation. | ||
=== Class vs struct === | |||
The only difference between '''struct''' and '''class''' is the default access level. | The only difference between '''struct''' and '''class''' is the default access level. | ||
Members in a class are private by default while members defined in '''struct''' are public. | Members in a class are private by default while members defined in '''struct''' are public. | ||
=== A simple class (C vs Qt) === | |||
Note that a constructor is not needed. | Note that a constructor is not needed. | ||
{| class="wikitable" | {| class="wikitable" | ||
Line 1,985: | Line 1,987: | ||
We can build the Cpp codes by '''g++ myclass.cpp main.cpp'''. | We can build the Cpp codes by '''g++ myclass.cpp main.cpp'''. | ||
=== Single colon and double colons === | |||
==== Single colon ==== | |||
* Single colon ":" was used in [http://www.cplusplus.com/doc/tutorial/inheritance/ inheritance]. For instance, | * Single colon ":" was used in [http://www.cplusplus.com/doc/tutorial/inheritance/ inheritance]. For instance, | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 2,005: | Line 2,007: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
==== Double colons ==== | |||
* Double colons was used to define/refer a class's function/method. Sometimes it can be used to resolve namespace problem. See [http://stackoverflow.com/questions/4269034/what-is-the-meaning-of-prepended-double-colon-to-class-name here]. | * Double colons was used to define/refer a class's function/method. Sometimes it can be used to resolve namespace problem. See [http://stackoverflow.com/questions/4269034/what-is-the-meaning-of-prepended-double-colon-to-class-name here]. | ||
<pre> | <pre> | ||
Line 2,011: | Line 2,013: | ||
</pre> | </pre> | ||
=== :: operator === | |||
The :: in the function name is the same scope operator. For example, [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter09/Student_info.cc <Student_info.cc>] in Accelerated C++, | The :: in the function name is the same scope operator. For example, [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter09/Student_info.cc <Student_info.cc>] in Accelerated C++, | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 2,056: | Line 2,058: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Accessor and Mutator === | |||
[https://stackoverflow.com/questions/9627093/what-is-the-difference-between-accessor-and-mutator-methods What is the difference between accessor and mutator methods?] An '''accessor''' is a class method used to read data members, while a '''mutator''' is a class method used to change data members. | [https://stackoverflow.com/questions/9627093/what-is-the-difference-between-accessor-and-mutator-methods What is the difference between accessor and mutator methods?] An '''accessor''' is a class method used to read data members, while a '''mutator''' is a class method used to change data members. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 2,069: | Line 2,071: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Access Member Functions === | |||
Use "." dot for regular objects. See the next session. | Use "." dot for regular objects. See the next session. | ||
For pointers to a class, use arrows "->". | For pointers to a class, use arrows "->". | ||
==== Pointers to classes ==== | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
// http://www.cplusplus.com/doc/tutorial/classes/ | // http://www.cplusplus.com/doc/tutorial/classes/ | ||
Line 2,104: | Line 2,106: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Access parent class data member === | |||
http://stackoverflow.com/questions/11525418/how-to-access-parent-classs-data-member-from-child-class-when-both-parent-and | http://stackoverflow.com/questions/11525418/how-to-access-parent-classs-data-member-from-child-class-when-both-parent-and | ||
=== Default constructor === | |||
The default constructor is the constructor that takes no parameters. It is called when an object is declared but is not initialized with any arguments. <span style="color: red">In fact, empty parentheses cannot be used to call the default constructor</span>. | The default constructor is the constructor that takes no parameters. It is called when an object is declared but is not initialized with any arguments. <span style="color: red">In fact, empty parentheses cannot be used to call the default constructor</span>. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 2,148: | Line 2,150: | ||
</pre> | </pre> | ||
=== Defining class member functions and member initializer list=== | |||
Use the single colon and a parenthesis. The parenthesis method can be used in the [http://www.cplusplus.com/doc/tutorial/variables/ general variables intialization]. | Use the single colon and a parenthesis. The parenthesis method can be used in the [http://www.cplusplus.com/doc/tutorial/variables/ general variables intialization]. | ||
Line 2,195: | Line 2,197: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== explicit keyword and implicit conversion to resolve the parameters to a function === | |||
http://stackoverflow.com/questions/121162/what-does-the-explicit-keyword-in-c-mean | http://stackoverflow.com/questions/121162/what-does-the-explicit-keyword-in-c-mean | ||
=== Class constructor can take parameter via assignment === | |||
For example (see p6 & p76 of the [[http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-096-introduction-to-c-january-iap-2011/lecture-notes/ MIT lecture note]) | For example (see p6 & p76 of the [[http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-096-introduction-to-c-january-iap-2011/lecture-notes/ MIT lecture note]) | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 2,219: | Line 2,221: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== copy constructor and copy assignment (operator=) === | |||
* See Chapter 11.3 of Accelerate C++ | * See Chapter 11.3 of Accelerate C++ | ||
* [http://www.cplusplus.com/articles/y8hv0pDG/ Cplusplus.com] | * [http://www.cplusplus.com/articles/y8hv0pDG/ Cplusplus.com] | ||
Line 2,246: | Line 2,248: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Operator Overloading === | |||
* http://www.learncpp.com/cpp-tutorial/91-introduction-to-operator-overloading/ | * http://www.learncpp.com/cpp-tutorial/91-introduction-to-operator-overloading/ | ||
* Chapter 11 Working with Classes -> Operator Overloading of C++ Primer Plus | * Chapter 11 Working with Classes -> Operator Overloading of C++ Primer Plus | ||
Line 2,295: | Line 2,297: | ||
</pre> | </pre> | ||
==== An example ==== | |||
From Chapter 11 of the C++ Primer Plus. | From Chapter 11 of the C++ Primer Plus. | ||
Line 2,330: | Line 2,332: | ||
|} | |} | ||
=== Friend functions & classes === | |||
* http://www.cplusplus.com/doc/tutorial/inheritance/ (w/ a complete example, the friend function does not below any any class) | * http://www.cplusplus.com/doc/tutorial/inheritance/ (w/ a complete example, the friend function does not below any any class) | ||
* <strike>http://www.cprogramming.com/tutorial/friends.html</strike> (the friend function belongs to anothe class but why does it not include an argument??, confusing) | * <strike>http://www.cprogramming.com/tutorial/friends.html</strike> (the friend function belongs to anothe class but why does it not include an argument??, confusing) | ||
Line 2,338: | Line 2,340: | ||
* Chapter 15 Friend classes in C++ Primer Plus. Friend classes are probably more practical than friend functions. | * Chapter 15 Friend classes in C++ Primer Plus. Friend classes are probably more practical than friend functions. | ||
==== Idea of friend functions ==== | |||
We want some general function (see examples below) or a member function of some class (see http://www.cprogramming.com/tutorial/friends.html) to access the (private, protected and public) members of one or more classes. | We want some general function (see examples below) or a member function of some class (see http://www.cprogramming.com/tutorial/friends.html) to access the (private, protected and public) members of one or more classes. | ||
Line 2,376: | Line 2,378: | ||
Other examples: '''std::ostream& operator<<''' operator as in [https://github.com/ekg/freebayes/search?utf8=%E2%9C%93&q=friend&type=Code freebayes] and [https://github.com/s-u/Rserve/search?utf8=%E2%9C%93&q=friend Rserve]. | Other examples: '''std::ostream& operator<<''' operator as in [https://github.com/ekg/freebayes/search?utf8=%E2%9C%93&q=friend&type=Code freebayes] and [https://github.com/s-u/Rserve/search?utf8=%E2%9C%93&q=friend Rserve]. | ||
==== More examples from operator functions ==== | |||
Consider the following (C++ Primer Plus) | Consider the following (C++ Primer Plus) | ||
<pre> | <pre> | ||
Line 2,393: | Line 2,395: | ||
See [https://github.com/arraytools/C/blob/master/c%2B%2Bprimerplus/Chapter%2011/mytime3.h <mytime3.h>] (the '''friend''' keyword in front of line 20 is required). It is a little tricky to understand the lines 20&21 at first. The function is a nonmember function (written in an inline way) and thus the keyword '''friend''' is necessary. | See [https://github.com/arraytools/C/blob/master/c%2B%2Bprimerplus/Chapter%2011/mytime3.h <mytime3.h>] (the '''friend''' keyword in front of line 20 is required). It is a little tricky to understand the lines 20&21 at first. The function is a nonmember function (written in an inline way) and thus the keyword '''friend''' is necessary. | ||
==== Overloading the << Operator ==== | |||
A common use of '''friend''' is overloading the << operator. | A common use of '''friend''' is overloading the << operator. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== Inheritance == | |||
* http://www.cplusplus.com/doc/tutorial/inheritance/ | * http://www.cplusplus.com/doc/tutorial/inheritance/ | ||
=== protected keyword in the base class === | |||
See an [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter13/Core.h example] from Accelerated C++ Chapter 13.1. | See an [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter13/Core.h example] from Accelerated C++ Chapter 13.1. | ||
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See the example in [http://www.cplusplus.com/doc/tutorial/inheritance/ cplusplus.com]. | See the example in [http://www.cplusplus.com/doc/tutorial/inheritance/ cplusplus.com]. | ||
=== Polymorphism === | |||
http://www.cplusplus.com/doc/tutorial/polymorphism/ | http://www.cplusplus.com/doc/tutorial/polymorphism/ | ||
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'''Function polymorphism''' is also called '''function overloading'''. | '''Function polymorphism''' is also called '''function overloading'''. | ||
=== '''Virtual''' functions === | |||
http://www.cplusplus.com/doc/tutorial/polymorphism/ | http://www.cplusplus.com/doc/tutorial/polymorphism/ | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== Template == | |||
C++ uses '''templates''' to enable '''generic programming''' techniques. The C++ Standard Library includes the Standard Template Library (STL) that provides a framework of templates for common data structures and algorithms. | C++ uses '''templates''' to enable '''generic programming''' techniques. The C++ Standard Library includes the Standard Template Library (STL) that provides a framework of templates for common data structures and algorithms. | ||
There are two kinds of templates: function templates (e.g. algorithm library) and class templates (e.g. array, vector, list containers). | There are two kinds of templates: function templates (e.g. algorithm library) and class templates (e.g. array, vector, list containers). | ||
=== Generic Programming & STL === | |||
* '''Generic programming''' is an approach to programming that focuses on algorithm reuse (to contrast, '''OOP''' focuses on data reuse). Read [http://www.cplusplus.com/forum/general/187031/ What is generic Programming ?]. For example, a ''find'' function would work with arrays (int, double,...) or linked lists or any other '''container''' type. That is, not only should the function be independent of the data type stored in the container, it should be independent of the data structure of the container itself. | * '''Generic programming''' is an approach to programming that focuses on algorithm reuse (to contrast, '''OOP''' focuses on data reuse). Read [http://www.cplusplus.com/forum/general/187031/ What is generic Programming ?]. For example, a ''find'' function would work with arrays (int, double,...) or linked lists or any other '''container''' type. That is, not only should the function be independent of the data type stored in the container, it should be independent of the data structure of the container itself. | ||
* A goal of generic programming is to write code that is independent of data types and data structures/'''containers'''. Templates are the C++ tools for creating generic programs. The '''STL''' goes further by providing a generic representation of algorithms. Chapter 16 of C++ Primer Plus. | * A goal of generic programming is to write code that is independent of data types and data structures/'''containers'''. Templates are the C++ tools for creating generic programs. The '''STL''' goes further by providing a generic representation of algorithms. Chapter 16 of C++ Primer Plus. | ||
=== Iterators (an extension of pointers) === | |||
'''Accelerated C++: Chapter 5. Using sequential containers and analyzing strings -> Iterators''' | '''Accelerated C++: Chapter 5. Using sequential containers and analyzing strings -> Iterators''' | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Function templates === | |||
http://www.cplusplus.com/doc/tutorial/templates/ | http://www.cplusplus.com/doc/tutorial/templates/ | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Class templates === | |||
http://www.cplusplus.com/doc/tutorial/templates/ | http://www.cplusplus.com/doc/tutorial/templates/ | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== Alternative to int == | |||
=== std::size_t === | |||
http://en.cppreference.com/w/cpp/types/size_t and http://www.cplusplus.com/reference/cstring/size_t/ | http://en.cppreference.com/w/cpp/types/size_t and http://www.cplusplus.com/reference/cstring/size_t/ | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== std::string::size_type === | |||
http://www.cplusplus.com/reference/string/string/ | http://www.cplusplus.com/reference/string/string/ | ||
Line 2,725: | Line 2,727: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== std::vector<TYPE>::size_type === | |||
http://www.cplusplus.com/reference/vector/vector/ | http://www.cplusplus.com/reference/vector/vector/ | ||
In vector, size_type is used as an index in a for-loop. See an example at [[#size_type|vector]] case. | In vector, size_type is used as an index in a for-loop. See an example at [[#size_type|vector]] case. | ||
== String, iterator and printing == | |||
* http://www.cplusplus.com/reference/string/string/begin/ | * http://www.cplusplus.com/reference/string/string/begin/ | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== snprintf() and sprintf() == | |||
See http://www.cplusplus.com/reference/cstdio/sprintf/ | See http://www.cplusplus.com/reference/cstdio/sprintf/ | ||
* int snprintf(char *s, size_t n, const char * format, ...) | * int snprintf(char *s, size_t n, const char * format, ...) | ||
* int sprintf(char *s, const char * format, ...) | * int sprintf(char *s, const char * format, ...) | ||
== String, string, string == | |||
[https://www.makeuseof.com/12-c-string-methods-you-should-master-today/ 12 C++ String Methods You Should Master Today] | |||
http://stackoverflow.com/questions/11322200/unable-to-build-my-c-code-with-g-4-6-3 | http://stackoverflow.com/questions/11322200/unable-to-build-my-c-code-with-g-4-6-3 | ||
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* Qt uses [http://doc.qt.io/qt-4.8/qstring.html QString] & [http://doc.qt.io/qt-4.8/qstringlist.html QStringList] from <QtCore>, [http://doc.qt.io/qt-4.8/qtextstream.html QTextStream] from <QTextStream>. Cf [http://doc.qt.io/qt-4.8/qdatastream.html QDataStream] from <QDataStream>. | * Qt uses [http://doc.qt.io/qt-4.8/qstring.html QString] & [http://doc.qt.io/qt-4.8/qstringlist.html QStringList] from <QtCore>, [http://doc.qt.io/qt-4.8/qtextstream.html QTextStream] from <QTextStream>. Cf [http://doc.qt.io/qt-4.8/qdatastream.html QDataStream] from <QDataStream>. | ||
=== Convert a c-style string to a c++ string === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
char * mystr = "klajlfdjlajfd"; | char * mystr = "klajlfdjlajfd"; | ||
Line 2,778: | Line 2,782: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== string::size_type === | |||
=== padding === | |||
* Use std::setw() http://stackoverflow.com/questions/667183/padding-stl-strings-in-c | * Use std::setw() http://stackoverflow.com/questions/667183/padding-stl-strings-in-c | ||
* Use "+" operation | * Use "+" operation | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Comparison === | |||
[http://www.cplusplus.com/reference/cstring/strcmp/ strcmp] and [http://www.cplusplus.com/reference/string/string/compare/ compare] | [http://www.cplusplus.com/reference/cstring/strcmp/ strcmp] and [http://www.cplusplus.com/reference/string/string/compare/ compare] | ||
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</pre> | </pre> | ||
=== Remove file name & Get the basename from a full path: substr(), find_last_of() === | |||
* These two actions correspond to the [https://en.wikipedia.org/wiki/Dirname dirname] and [https://en.wikipedia.org/wiki/Basename basename] commands in Linux OS. | * These two actions correspond to the [https://en.wikipedia.org/wiki/Dirname dirname] and [https://en.wikipedia.org/wiki/Basename basename] commands in Linux OS. | ||
* Use [http://en.cppreference.com/w/cpp/string/basic_string/find_last_of string::find_last_of()] and [http://www.cplusplus.com/reference/string/string/substr/ string::substr()] functions. See http://stackoverflow.com/questions/10364877/c-how-to-remove-filename-from-path-string | * Use [http://en.cppreference.com/w/cpp/string/basic_string/find_last_of string::find_last_of()] and [http://www.cplusplus.com/reference/string/string/substr/ string::substr()] functions. See http://stackoverflow.com/questions/10364877/c-how-to-remove-filename-from-path-string | ||
Line 2,855: | Line 2,859: | ||
</pre> | </pre> | ||
=== Extract the file name and extension from a string: find_last_of() === | |||
https://stackoverflow.com/questions/4430780/how-can-i-extract-the-file-name-and-extension-from-a-path-in-c | https://stackoverflow.com/questions/4430780/how-can-i-extract-the-file-name-and-extension-from-a-path-in-c | ||
=== Replace a substring === | |||
* Use the [http://en.cppreference.com/w/cpp/string/basic_string/find string::find()] or ([http://www.cplusplus.com/reference/string/string/find/ this]) and [http://en.cppreference.com/w/cpp/string/basic_string/replace string::replace()] functions. See http://stackoverflow.com/questions/3418231/replace-part-of-a-string-with-another-string | * Use the [http://en.cppreference.com/w/cpp/string/basic_string/find string::find()] or ([http://www.cplusplus.com/reference/string/string/find/ this]) and [http://en.cppreference.com/w/cpp/string/basic_string/replace string::replace()] functions. See http://stackoverflow.com/questions/3418231/replace-part-of-a-string-with-another-string | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 2,884: | Line 2,888: | ||
</pre> | </pre> | ||
=== convert backslash to forward slash in string === | |||
In C++ (not tested) | In C++ (not tested) | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== size method == | |||
* [http://www.cplusplus.com/reference/string/string/size/ string object]: Returns the length of the string, in terms of bytes. | * [http://www.cplusplus.com/reference/string/string/size/ string object]: Returns the length of the string, in terms of bytes. | ||
* [http://www.cplusplus.com/reference/vector/vector/size/ vector object]: Return the number of elements. | * [http://www.cplusplus.com/reference/vector/vector/size/ vector object]: Return the number of elements. | ||
== Convert == | |||
=== Danger of implicit type conversion === | |||
Implicit type conversion (coercion) can result in unexpected results. See the following example. | Implicit type conversion (coercion) can result in unexpected results. See the following example. | ||
<syntaxhighlight lang='bash'> | <syntaxhighlight lang='bash'> | ||
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* long int to int drops the encoded higher bits | * long int to int drops the encoded higher bits | ||
=== Convert char* to string === | |||
std::string has a constructor that takes a char*. | std::string has a constructor that takes a char*. | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
=== Convert [http://en.wikipedia.org/wiki/String_(C%2B%2B) std::string] to [https://en.wikipedia.org/wiki/C_string_handling c-string/char *] === | |||
See | See | ||
* [http://stackoverflow.com/questions/347949/convert-stdstring-to-const-char-or-char stackoverflow A] | * [http://stackoverflow.com/questions/347949/convert-stdstring-to-const-char-or-char stackoverflow A] | ||
Line 2,956: | Line 2,960: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Convert an integer to character string === | |||
See [http://www.cplusplus.com/articles/D9j2Nwbp/ www.cplusplus.com]. | See [http://www.cplusplus.com/articles/D9j2Nwbp/ www.cplusplus.com]. | ||
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</pre> | </pre> | ||
=== Convert a numerical number to char === | |||
Use | Use | ||
<pre> | <pre> | ||
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This will save a number for example -7.035425 to -7.03 as characters. | This will save a number for example -7.035425 to -7.03 as characters. | ||
== C++ IO Streams == | |||
* http://www.cprogramming.com/tutorial/c++-iostreams.html | * http://www.cprogramming.com/tutorial/c++-iostreams.html | ||
* http://www.cplusplus.com/doc/tutorial/files/ | * http://www.cplusplus.com/doc/tutorial/files/ | ||
Line 3,034: | Line 3,038: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== No matching function - ifstream open() === | |||
If we want to use a '''string''' type as a file name instead of specifying the file name in the code (hard-code), we need to use the '''c_str''' member function first. | If we want to use a '''string''' type as a file name instead of specifying the file name in the code (hard-code), we need to use the '''c_str''' member function first. | ||
Line 3,061: | Line 3,065: | ||
Support for std::string argument was added in c++11. | Support for std::string argument was added in c++11. | ||
=== fail(), bad() and eof() functions === | |||
* http://www.cplusplus.com/reference/ios/ios/bad/ | * http://www.cplusplus.com/reference/ios/ios/bad/ | ||
* http://en.cppreference.com/w/cpp/io/basic_ifstream | * http://en.cppreference.com/w/cpp/io/basic_ifstream | ||
Line 3,070: | Line 3,074: | ||
[http://en.cppreference.com/w/cpp/io/basic_ios/bad Here] is an example from cppreference.com to test bad(), eof() and fail() methods. | [http://en.cppreference.com/w/cpp/io/basic_ios/bad Here] is an example from cppreference.com to test bad(), eof() and fail() methods. | ||
== stringstream == | |||
* http://www.cplusplus.com/reference/sstream/stringstream/ | * http://www.cplusplus.com/reference/sstream/stringstream/ | ||
* http://en.cppreference.com/w/cpp/io/basic_stringstream | * http://en.cppreference.com/w/cpp/io/basic_stringstream | ||
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Since stringstream is based on sstream, a stringstream is closer to stream (or file) rather than a string. | Since stringstream is based on sstream, a stringstream is closer to stream (or file) rather than a string. | ||
=== Simple example (using multiple << and >> operators) === | |||
<pre> | <pre> | ||
// swapping ostringstream objects | // swapping ostringstream objects | ||
Line 3,102: | Line 3,106: | ||
</pre> | </pre> | ||
=== stringstream::str === | |||
<syntaxhighlight lang='c'> | <syntaxhighlight lang='c'> | ||
#include <string> // std::string | #include <string> // std::string | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Clean/empty a stringstream === | |||
See [http://en.cppreference.com/w/cpp/io/basic_stringstream/str stringstream]. | See [http://en.cppreference.com/w/cpp/io/basic_stringstream/str stringstream]. | ||
<syntaxhighlight lang='c'> | <syntaxhighlight lang='c'> | ||
Line 3,128: | Line 3,132: | ||
P.S. The clear() member function is inherited from ios and is used to clear the error state of the stream only. For some reason, it is necessary to use the clear() function inside a loop call. Another method is to declare a stringstream variable inside a loop. | P.S. The clear() member function is inherited from ios and is used to clear the error state of the stream only. For some reason, it is necessary to use the clear() function inside a loop call. Another method is to declare a stringstream variable inside a loop. | ||
=== clear() and rdstate() functions === | |||
'''stringstream''' is related to reading. We call clear() to reset the error state, which tells the library that input can continue despite the failure. Note that clear() is also used in '''vector''' objects. | '''stringstream''' is related to reading. We call clear() to reset the error state, which tells the library that input can continue despite the failure. Note that clear() is also used in '''vector''' objects. | ||
Line 3,245: | Line 3,249: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== getline() function to extract === | |||
* See [[#Read_a_text_file_with_multiple_rows_.28using_stringstream_and_getline.28.29.29|this section]]. | * See [[#Read_a_text_file_with_multiple_rows_.28using_stringstream_and_getline.28.29.29|this section]]. | ||
* http://en.cppreference.com/w/cpp/io/basic_istream/getline | * http://en.cppreference.com/w/cpp/io/basic_istream/getline | ||
== istream/ostream, iostream and fstream headers and files == | |||
[https://opensource.com/article/21/3/ccc-input-output How to read and write files in C++] I/O stream classes | |||
See 4.1.2 the standard-library headers and namespace in The C++ Programming Language. The standard library is defined in a namespace called '''std'''. | See 4.1.2 the standard-library headers and namespace in The C++ Programming Language. The standard library is defined in a namespace called '''std'''. | ||
# [http://www.cplusplus.com/reference/iostream/ iostream] include cin, cout, cerr, clog, [http://www.cplusplus.com/reference/istream/ istream] and [http://www.cplusplus.com/reference/ostream/ ostream] | # [http://www.cplusplus.com/reference/iostream/ iostream] include cin, cout, cerr, clog, [http://www.cplusplus.com/reference/istream/ istream] and [http://www.cplusplus.com/reference/ostream/ ostream] | ||
Line 3,256: | Line 3,262: | ||
(10.5.2 in Accelerated C++) It is possible to use an ''ifstream'' wherever the library expects an ''istream'' and an ''ofstream'' wherever the library expects an ''ostream''??? | (10.5.2 in Accelerated C++) It is possible to use an ''ifstream'' wherever the library expects an ''istream'' and an ''ofstream'' wherever the library expects an ''ostream''??? | ||
== Read from console: '''[http://www.cplusplus.com/reference/iostream/cin/ std::cin >>]''' == | |||
We need to include the header file <iostream>. | We need to include the header file <iostream>. | ||
Note that this is different from '''[http://www.cplusplus.com/reference/istream/istream/ std::istream read()]''' which requires the header file <fstream> and it is used for accessing files. | Note that this is different from '''[http://www.cplusplus.com/reference/istream/istream/ std::istream read()]''' which requires the header file <fstream> and it is used for accessing files. | ||
=== What is std::cin and if (cin >> x) === | |||
https://stackoverflow.com/questions/6791520/if-cin-x-why-can-you-use-that-condition | https://stackoverflow.com/questions/6791520/if-cin-x-why-can-you-use-that-condition | ||
Line 3,274: | Line 3,280: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Create a vector: input from cin === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
#include <iostream> | #include <iostream> | ||
Line 3,320: | Line 3,326: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Create a map (key-index vector) object (word count) === | |||
This is example code from Chapter 21.6.1 "Map" of PPP. | This is example code from Chapter 21.6.1 "Map" of PPP. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 3,355: | Line 3,361: | ||
It seems the words are sorted too. | It seems the words are sorted too. | ||
== Directory == | |||
=== Check if a directory exists or not === | |||
http://stackoverflow.com/questions/3828192/checking-if-a-directory-exists-in-unix-system-call | http://stackoverflow.com/questions/3828192/checking-if-a-directory-exists-in-unix-system-call | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 3,369: | Line 3,375: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Create a directory in Linux === | |||
http://codeyarns.com/2014/08/07/how-to-create-directory-using-c-on-linux/ | http://codeyarns.com/2014/08/07/how-to-create-directory-using-c-on-linux/ | ||
<syntaxhighlight lang='bash'> | <syntaxhighlight lang='bash'> | ||
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Note that this does not create parent directories . | Note that this does not create parent directories . | ||
=== List files in a directory === | |||
http://www.linuxquestions.org/questions/programming-9/c-list-files-in-directory-379323/ | http://www.linuxquestions.org/questions/programming-9/c-list-files-in-directory-379323/ | ||
== File == | |||
=== Delete a file === | |||
Use C library [http://www.cplusplus.com/reference/cstdio/ '''stdio''']; i.e. include <stdio.h> or <cstdio>. See also [http://en.cppreference.com/w/cpp/io/c/remove remove]. Note that according to '''The Linux Programming Interface''' book, remove() function removes a file or an empty directory. The empty directory part was not mentioned on website?? | Use C library [http://www.cplusplus.com/reference/cstdio/ '''stdio''']; i.e. include <stdio.h> or <cstdio>. See also [http://en.cppreference.com/w/cpp/io/c/remove remove]. Note that according to '''The Linux Programming Interface''' book, remove() function removes a file or an empty directory. The empty directory part was not mentioned on website?? | ||
Line 3,428: | Line 3,434: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== Reading a table file == | |||
=== Line ending difference between DOS and UNIX text file === | |||
The DOS text file has two ending characters (CR + LF) while UNIX text file has only 1 ending character (LF). This may create two answers when we want to count the number of columns in a row or compare the elements from the last column. | The DOS text file has two ending characters (CR + LF) while UNIX text file has only 1 ending character (LF). This may create two answers when we want to count the number of columns in a row or compare the elements from the last column. | ||
Line 3,467: | Line 3,473: | ||
</pre> | </pre> | ||
=== Count number of lines in a text file --- '''[http://www.cplusplus.com/reference/fstream/ifstream/?kw=ifstream std::ifstream]''' & getline() === | |||
We need to include the header <fstream>. | We need to include the header <fstream>. | ||
Line 3,538: | Line 3,544: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Read a text file and one character at a time (using get()) === | |||
<syntaxhighlight lang="cpp"> | <syntaxhighlight lang="cpp"> | ||
void foo(ifstream& fin, ofstrea& fout) | void foo(ifstream& fin, ofstrea& fout) | ||
Line 3,556: | Line 3,562: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Read a text file with one row only (using getline()) === | |||
<syntaxhighlight lang="cpp"> | <syntaxhighlight lang="cpp"> | ||
#include <iostream> | #include <iostream> | ||
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* The output is the same if the end of line is in DOS format (CR + LF). | * The output is the same if the end of line is in DOS format (CR + LF). | ||
=== Read a text file with multiple columns --- std::stringstream and getline() === | |||
With the following examples, we can count the number of columns and number of rows of a text file. | With the following examples, we can count the number of columns and number of rows of a text file. | ||
Line 3,639: | Line 3,645: | ||
cout << item << endl; | cout << item << endl; | ||
} | } | ||
// For numerical data, we can use | |||
// double value; | |||
// while (iss >> value) { } | |||
iss.clear(); // step 5. clear the error state of the stream? | iss.clear(); // step 5. clear the error state of the stream? | ||
} | } | ||
cout << "There are " << nrow << " rows and " << ncol " columns\n"; | cout << "There are " << nrow << " rows and " << ncol << " columns\n"; | ||
fin.close(); | fin.close(); | ||
} | } | ||
Line 3,691: | Line 3,700: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== reset position to the beginning of file === | |||
<pre> | <pre> | ||
ifstream orderfile; | ifstream orderfile; | ||
Line 3,709: | Line 3,718: | ||
</pre> | </pre> | ||
== Write a Function to Contain an Argument of Output Device (eg file, screen) == | |||
See Listing 8.8 [https://github.com/arraytools/C/blob/master/c%2B%2Bprimerplus/Chapter%208/filefunct.cpp <filefunc.cpp>] in C++ Primer Plus (5th ed). It uses '''ostream &''' as the class of output device type in the function definition. For the main function, we can use objects of class '''ofstream''' or '''istream'''. Recall, ostream is a '''base class''' and ofstream is a '''derived class'''. | See Listing 8.8 [https://github.com/arraytools/C/blob/master/c%2B%2Bprimerplus/Chapter%208/filefunct.cpp <filefunc.cpp>] in C++ Primer Plus (5th ed). It uses '''ostream &''' as the class of output device type in the function definition. For the main function, we can use objects of class '''ofstream''' or '''istream'''. Recall, ostream is a '''base class''' and ofstream is a '''derived class'''. | ||
Line 3,742: | Line 3,751: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== Sorting only == | |||
* [http://stackoverflow.com/questions/12459290/how-to-compare-c-string-using-qsort-in-c C++ string sorting] Note: qsort() in C won't work for string type in C++. | * [http://stackoverflow.com/questions/12459290/how-to-compare-c-string-using-qsort-in-c C++ string sorting] Note: qsort() in C won't work for string type in C++. | ||
<pre> | <pre> | ||
Line 3,781: | Line 3,790: | ||
Note: The use of '''ostream_iterator<string>(cout, "\n")''' was explained & used in Accelerated C++ Chapter 8.3 (Input and output iterators) & 8.4. It was also explained in [http://www.cplusplus.com/reference/iterator/ostream_iterator/ cplusplus.com]. | Note: The use of '''ostream_iterator<string>(cout, "\n")''' was explained & used in Accelerated C++ Chapter 8.3 (Input and output iterators) & 8.4. It was also explained in [http://www.cplusplus.com/reference/iterator/ostream_iterator/ cplusplus.com]. | ||
== Return permutation (R's order() function) using 3 approaches == | |||
* http://stackoverflow.com/questions/4523220/sorting-a-vector-of-double-precision-reals-and-obtain-their-order | * http://stackoverflow.com/questions/4523220/sorting-a-vector-of-double-precision-reals-and-obtain-their-order | ||
Line 3,914: | Line 3,923: | ||
This also gives the same result. In fact, the code is so general: if I add '''#include <string>''' and change '''double''' to '''std::string''' in the declaration of ''values'', the code works for string data type. | This also gives the same result. In fact, the code is so general: if I add '''#include <string>''' and change '''double''' to '''std::string''' in the declaration of ''values'', the code works for string data type. | ||
== Infinity value == | |||
http://en.cppreference.com/w/cpp/types/numeric_limits/infinity | http://en.cppreference.com/w/cpp/types/numeric_limits/infinity | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 3,923: | Line 3,932: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== Scope == | |||
Method 1: Created object cannot be used in other places. | Method 1: Created object cannot be used in other places. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 3,952: | Line 3,961: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== C++11 == | |||
* http://www.stroustrup.com/ and [http://www.stroustrup.com/C++11FAQ.html C++FAQ] | * http://www.stroustrup.com/ and [http://www.stroustrup.com/C++11FAQ.html C++FAQ] | ||
* [http://www.codeproject.com/Articles/570638/Ten-Cplusplus-Features-Every-Cplusplus-Developer Ten C++11 Features Every C++ Developer Should Use] | * [http://www.codeproject.com/Articles/570638/Ten-Cplusplus-Features-Every-Cplusplus-Developer Ten C++11 Features Every C++ Developer Should Use] | ||
Line 3,964: | Line 3,973: | ||
</pre> | </pre> | ||
=== regex === | |||
* http://www.cplusplus.com/reference/regex/ | * http://www.cplusplus.com/reference/regex/ | ||
* http://en.cppreference.com/w/cpp/regex/ | * http://en.cppreference.com/w/cpp/regex/ | ||
Line 3,989: | Line 3,998: | ||
See [http://stackoverflow.com/questions/1318279/regex-to-match-a-string-that-doesnt-contain-a-certain-string this post] to match a string that does not contain some string. | See [http://stackoverflow.com/questions/1318279/regex-to-match-a-string-that-doesnt-contain-a-certain-string this post] to match a string that does not contain some string. | ||
=== Lambda functions === | |||
A lambda function is essentially an anonymous function (a function without a name) that’s defined inline. | A lambda function is essentially an anonymous function (a function without a name) that’s defined inline. | ||
* http://www.cprogramming.com/c++11/c++11-lambda-closures.html | * http://www.cprogramming.com/c++11/c++11-lambda-closures.html | ||
Line 4,013: | Line 4,022: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== STL vector vs C++ new == | |||
* http://lemire.me/blog/archives/2012/06/20/do-not-waste-time-with-stl-vectors/ | * http://lemire.me/blog/archives/2012/06/20/do-not-waste-time-with-stl-vectors/ | ||
Line 4,103: | Line 4,112: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== convert a C-style array to a c++ vector === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
#include <vector> | #include <vector> | ||
Line 4,111: | Line 4,120: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== WINVER == | |||
http://stackoverflow.com/questions/1439752/what-is-winver | http://stackoverflow.com/questions/1439752/what-is-winver | ||
WINVER determines the minimum platform SDK required to build your application, which in turn will determine at compile time which routines are found by the headers. | WINVER determines the minimum platform SDK required to build your application, which in turn will determine at compile time which routines are found by the headers. | ||
Line 4,119: | Line 4,128: | ||
This was used in win32 disk imager program. | This was used in win32 disk imager program. | ||
== Period == | |||
[http://stackoverflow.com/questions/1238613/what-is-the-difference-between-the-dot-operator-and-in-c What is the difference between the dot (.) operator and -> in C++?] | [http://stackoverflow.com/questions/1238613/what-is-the-difference-between-the-dot-operator-and-in-c What is the difference between the dot (.) operator and -> in C++?] | ||
Line 4,126: | Line 4,135: | ||
Member Access Operators: . and -> from [http://msdn.microsoft.com/en-us/library/b930c881.aspx msdn.microsoft.com] | Member Access Operators: . and -> from [http://msdn.microsoft.com/en-us/library/b930c881.aspx msdn.microsoft.com] | ||
== Protected vs private members == | |||
See [http://stackoverflow.com/questions/224966/private-and-protected-members-c here] or [http://www.cs.rit.edu/~mjh/docs/c++-faq/private-inheritance.html C++ FAQ] | See [http://stackoverflow.com/questions/224966/private-and-protected-members-c here] or [http://www.cs.rit.edu/~mjh/docs/c++-faq/private-inheritance.html C++ FAQ] | ||
Line 4,137: | Line 4,146: | ||
Edit 2: Use whatever makes sense in the context of your problem. You should try to make members private whenever you can to reduce coupling and protect the implementation of the base class, but if that's not possible then use protected members. Check C++ FAQ Lite for a better understanding of the issue. This question about protected variables might also help. | Edit 2: Use whatever makes sense in the context of your problem. You should try to make members private whenever you can to reduce coupling and protect the implementation of the base class, but if that's not possible then use protected members. Check C++ FAQ Lite for a better understanding of the issue. This question about protected variables might also help. | ||
== alignment of pointers == | |||
https://stat.ethz.ch/pipermail/r-devel/2013-August/067314.html | https://stat.ethz.ch/pipermail/r-devel/2013-August/067314.html | ||
=== Find sample quantiles (percentiles) using STL | == Generate random numbers == | ||
* [http://www.cplusplus.com/reference/cstdlib/srand/ srand()], rand() and [http://www.cplusplus.com/reference/cstdlib/RAND_MAX/ RAND_MAX] | |||
* [https://stackoverflow.com/a/6219525 How to generate a random number between 0 and 1?] | |||
* By default, calling '''rand()''' will create [https://www.geeksforgeeks.org/rand-and-srand-in-ccpp/ same sequence of random numbers on every program run] | |||
: <syntaxhighlight lang='c'> | |||
#include <stdio.h> | |||
#include <stdlib.h> | |||
int main(void) | |||
{ | |||
// This program will create same sequence of | |||
// random numbers on every program run | |||
for(int i = 0; i<5; i++) | |||
printf(" %d ", rand()); | |||
return 0; | |||
} | |||
</syntaxhighlight> | |||
* '''If you don’t call srand before your first call to rand, it’s as if you had called srand(1) to set the seed to one.''' | |||
: <syntaxhighlight lang='c'> | |||
#include <stdio.h> | |||
#include <stdlib.h> | |||
#include<time.h> | |||
int main(void) | |||
{ | |||
for(int i = 0; i<5; i++) | |||
printf(" %d ", rand()); | |||
printf("\n"); | |||
srand(1234); | |||
for(int i = 0; i<5; i++) | |||
printf(" %d ", rand()); | |||
printf("\n"); | |||
srand(1); | |||
for(int i = 0; i<5; i++) | |||
printf(" %d ", rand()); | |||
printf("\n"); | |||
return 0; | |||
} | |||
/* output from Ubuntu 16.04 (gcc 5.4.0), CentOS 7 (gcc 4.8.5) or Debian 10 (gcc 8.3.0) | |||
1804289383 846930886 1681692777 1714636915 1957747793 | |||
479142414 465566339 961126155 1057886067 1222702060 | |||
1804289383 846930886 1681692777 1714636915 1957747793 | |||
output from Mac 10.14.5 (Apple LLVM version 10.0.1) | |||
16807 282475249 1622650073 984943658 1144108930 | |||
20739838 682106452 895431078 2092213417 933663541 | |||
16807 282475249 1622650073 984943658 1144108930 | |||
*/ | |||
</syntaxhighlight> | |||
* [https://stackoverflow.com/a/922385 srand() + rand() result is not the same/consistent across platforms]. Solutions | |||
** C++11 Mersenne Twister/mt19937. http://www.cplusplus.com/reference/random/mt19937/, [https://www.guyrutenberg.com/2014/05/03/c-mt19937-example/ examples], [https://en.cppreference.com/w/cpp/numeric/random cppreference.com]. | |||
** http://www.cs.wm.edu/~va/software/park/ as referenced by [https://social.msdn.microsoft.com/Forums/vstudio/en-US/05f6bd7c-5543-4b72-bd6d-3bc9bd6b78be/running-c-rand-and-srand-on-different-computersos Running C++ rand and srand on different computers/OS] | |||
* [https://stackoverflow.com/a/48730423 If we seed c++11 mt19937 as the same on different machines, will we get the same sequence of random numbers?]. Yes. The following example should be corrected by breaking multiple "<<" to separate lines since [https://stackoverflow.com/a/14810222 the order of execution in operator << may depend on the compiler]. After I break the line into two, the Ubuntu returns the same result as Mac gives. See also [https://en.cppreference.com/w/cpp/language/eval_order Order of evaluation] from cppreference.com. | |||
: <syntaxhighlight lang='cpp'> | |||
#include <iostream> | |||
#include <random> | |||
using namespace std; | |||
int main() | |||
{ | |||
mt19937 mt_rand(1234); | |||
cout << mt_rand() << ' ' << mt_rand() << endl; | |||
return 0; | |||
} | |||
/* g++ -std=c++11 test.cpp; ./a.out | |||
Linux (Ubuntu, Debian, CentOS; do "yum install gcc gcc-c++" first) | |||
2137449171 822569775 | |||
Mac, Raspbian armv6l (reverse order compared to Linux) | |||
822569775 2137449171 | |||
*/ | |||
</syntaxhighlight> | |||
== Find sample quantiles (percentiles) using STL == | |||
STL algorithms defined in the <algorithm> and <numeric> libraries. | STL algorithms defined in the <algorithm> and <numeric> libraries. | ||
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</pre> | </pre> | ||
== Calculate execution time == | |||
http://stackoverflow.com/questions/5248915/execution-time-of-c-program. The following code is from [http://www.simonmonk.org/?page_id=370 Programming Arduino Next Steps]. It took .04 seconds on Xeon W3690 @ 3.47GHz and 28 seconds on Arduino Uno. | http://stackoverflow.com/questions/5248915/execution-time-of-c-program. The following code is from [http://www.simonmonk.org/?page_id=370 Programming Arduino Next Steps]. It took .04 seconds on Xeon W3690 @ 3.47GHz and 28 seconds on Arduino Uno. | ||
<syntaxhighlight lang='c'> | <syntaxhighlight lang='c'> | ||
Line 4,238: | Line 4,321: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== Time the iterations from 0 to 2147483647 === | |||
<syntaxhighlight lang='c'> | <syntaxhighlight lang='c'> | ||
#include <iostream> | #include <iostream> | ||
Line 4,279: | Line 4,362: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== execute a command line command from a C++ program == | |||
* Use the [http://linux.die.net/man/3/system system()] function - http://stackoverflow.com/questions/10931134/return-value-of-system-function-call-in-c-used-to-run-a-python-program | * Use the [http://linux.die.net/man/3/system system()] function - http://stackoverflow.com/questions/10931134/return-value-of-system-function-call-in-c-used-to-run-a-python-program | ||
<syntaxhighlight lang='bash'> | <syntaxhighlight lang='bash'> | ||
Line 4,305: | Line 4,388: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== Check OS == | |||
http://stackoverflow.com/questions/142508/how-do-i-check-os-with-a-preprocessor-directive | http://stackoverflow.com/questions/142508/how-do-i-check-os-with-a-preprocessor-directive | ||
Line 4,316: | Line 4,399: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== Check Visual Studio compiler == | |||
'''_MSC_VER''' macro. See | '''_MSC_VER''' macro. See | ||
* https://stackoverflow.com/questions/70013/how-to-detect-if-im-compiling-code-with-visual-studio-2008 | * https://stackoverflow.com/questions/70013/how-to-detect-if-im-compiling-code-with-visual-studio-2008 | ||
Line 4,330: | Line 4,413: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
== C libraries | == Short examples == | ||
* [https://www.makeuseof.com/find-lcm-gcd-of-two-numbers/ How to Find the LCM and GCD of Two Numbers in Multiple Languages] | |||
* [https://www.makeuseof.com/cpp-code-snippets-everyday-programming/ 11 C++ Code Snippets for Everyday Programming Problems] | |||
= C libraries = | |||
* http://www.cplusplus.com/reference/clibrary/ | * http://www.cplusplus.com/reference/clibrary/ | ||
== cctype == | |||
== cerrno == | |||
== climits == | |||
== cmath == | |||
== cstddef == | |||
== cstdio == | |||
== cstdlib == | |||
http://www.cplusplus.com/reference/cstdlib/ | http://www.cplusplus.com/reference/cstdlib/ | ||
abs(), free(), malloc(), exit(), rand(), system(), getenv(), NULL and some string function. | abs(), free(), malloc(), exit(), rand(), system(), getenv(), NULL and some string function. | ||
== cstring == | |||
== ctime == | |||
= C++ standard libraries = | |||
* [http://en.cppreference.com/w/cpp cppreference.com] | * [http://en.cppreference.com/w/cpp cppreference.com] | ||
* [http://en.wikipedia.org/wiki/C%2B%2B_Standard_Library wikipedia] | * [http://en.wikipedia.org/wiki/C%2B%2B_Standard_Library wikipedia] | ||
Line 4,352: | Line 4,439: | ||
* [http://cppstdlib.com/ The C++ Standard Library - A Tutorial and Reference] by Nicolai M. Josuttis and [https://www.amazon.com/Standard-Library-Tutorial-Reference-2nd/dp/0321623215 reviews] from amazon. | * [http://cppstdlib.com/ The C++ Standard Library - A Tutorial and Reference] by Nicolai M. Josuttis and [https://www.amazon.com/Standard-Library-Tutorial-Reference-2nd/dp/0321623215 reviews] from amazon. | ||
== STL and c++ standard library == | |||
* [http://en.wikipedia.org/wiki/C%2B%2B_Standard_Library C++ standard library] from wikipedia. | * [http://en.wikipedia.org/wiki/C%2B%2B_Standard_Library C++ standard library] from wikipedia. | ||
* [http://stackoverflow.com/questions/5205491/whats-this-stl-vs-c-standard-library-fight-all-about STL vs C++ standard library]. STL was written in the days long before C++ was standardized. Parts of the C++ Standard Library were based on parts of the STL, and it is these parts that many people (including several authors and the notoriously error-ridden cplusplus.com) still refer to as "the STL". However, this is inaccurate; indeed, the C++ standard never mentions "STL", and there are content differences between the two. | * [http://stackoverflow.com/questions/5205491/whats-this-stl-vs-c-standard-library-fight-all-about STL vs C++ standard library]. STL was written in the days long before C++ was standardized. Parts of the C++ Standard Library were based on parts of the STL, and it is these parts that many people (including several authors and the notoriously error-ridden cplusplus.com) still refer to as "the STL". However, this is inaccurate; indeed, the C++ standard never mentions "STL", and there are content differences between the two. | ||
=== | === Using C and C++ for data science === | ||
==== Four categories | [https://opensource.com/article/20/2/c-data-science Using C and C++ for data science] - work through a common data science task with C99 and C++11. Printing. Reading data. Fitting data. Plotting. clang++. | ||
== Containers == | |||
=== Four categories === | |||
# <span style="color: blue">'''Sequence containers'''</span>: vector, array, deque, list, forward_list. | # <span style="color: blue">'''Sequence containers'''</span>: vector, array, deque, list, forward_list. | ||
# <span style="color: blue">'''Associative containers'''</span>: map, set, multimap, multiset. | # <span style="color: blue">'''Associative containers'''</span>: map, set, multimap, multiset. | ||
Line 4,365: | Line 4,455: | ||
The most important containers are '''vector''', '''list''' and '''map'''. | The most important containers are '''vector''', '''list''' and '''map'''. | ||
=== Common operations === | |||
See Accelerated C++ 5.9. | See Accelerated C++ 5.9. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 4,426: | Line 4,516: | ||
toupper(c) | toupper(c) | ||
tolower(c) | tolower(c) | ||
=== vector === | |||
http://www.cplusplus.com/reference/vector/vector/ | http://www.cplusplus.com/reference/vector/vector/ | ||
==== push_back() method ==== | |||
http://www.cplusplus.com/reference/vector/vector/push_back/ | http://www.cplusplus.com/reference/vector/vector/push_back/ | ||
The vector length does not have to be determined beforehand. The '''push_back()''' method can be used to insert an element to the end of a vector object. | The vector length does not have to be determined beforehand. The '''push_back()''' method can be used to insert an element to the end of a vector object. | ||
==== clear() method ==== | |||
Removes all elements from the vector (which are destroyed), leaving the container with a size of 0. See http://www.cplusplus.com/reference/vector/vector/clear/. | Removes all elements from the vector (which are destroyed), leaving the container with a size of 0. See http://www.cplusplus.com/reference/vector/vector/clear/. | ||
==== resize() method ==== | |||
See an application of [http://www.cplusplus.com/reference/algorithm/transform/ transform]. | See an application of [http://www.cplusplus.com/reference/algorithm/transform/ transform]. | ||
==== Vector of own type ==== | |||
* See Accelerated C++ Chapter 4. See <[https://github.com/arraytools/C/tree/master/accelerated_unix/chapter04 main2.cc]> program which is a standalone program which does not depend on other source. Below it gives an example of the output: | * See Accelerated C++ Chapter 4. See <[https://github.com/arraytools/C/tree/master/accelerated_unix/chapter04 main2.cc]> program which is a standalone program which does not depend on other source. Below it gives an example of the output: | ||
<syntaxhighlight lang='bash'> | <syntaxhighlight lang='bash'> | ||
Line 4,452: | Line 4,542: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
==== size_type ==== | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
vector<int>::size_type x; | vector<int>::size_type x; | ||
Line 4,475: | Line 4,565: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
==== square bracket operator ==== | |||
For example, | For example, | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 4,486: | Line 4,576: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
==== 2 dimensional matrix ==== | |||
* http://www.cplusplus.com/forum/articles/7459/ | * http://www.cplusplus.com/forum/articles/7459/ | ||
* [https://www.makeuseof.com/add-and-subtract-two-matrices/ How to Add and Subtract Two Matrices in C++, Python, and JavaScript] | |||
* http://stackoverflow.com/questions/12841170/how-to-define-a-2d-array-in-c-and-stl-without-memory-manipulation | * http://stackoverflow.com/questions/12841170/how-to-define-a-2d-array-in-c-and-stl-without-memory-manipulation | ||
Line 4,592: | Line 4,683: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
==== Comparison of a C++ array and C++ '''vector''' ==== | |||
See the example from PPP Chapter 20.1. | See the example from PPP Chapter 20.1. | ||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
Line 4,645: | Line 4,736: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== list === | |||
(From The C++ PL) A '''list''' is a double-linked list. We use a '''list''' for sequences where we want to insert and delete elements without moving other elements. | (From The C++ PL) A '''list''' is a double-linked list. We use a '''list''' for sequences where we want to insert and delete elements without moving other elements. | ||
Line 4,703: | Line 4,794: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== map === | |||
A map is like a vector but using a key instead of an integer to index it (R's vector object can do it already; see [https://cran.r-project.org/doc/manuals/r-release/R-intro.html#Index-vectors An introduction to R]). | A map is like a vector but using a key instead of an integer to index it (R's vector object can do it already; see [https://cran.r-project.org/doc/manuals/r-release/R-intro.html#Index-vectors An introduction to R]). | ||
Line 4,747: | Line 4,838: | ||
</pre> | </pre> | ||
=== array === | |||
=== deque === | |||
=== queue === | |||
=== set === | |||
=== stack === | |||
=== unordered_map === | |||
=== unordered_set === | |||
== [http://www.cplusplus.com/reference/algorithm/ Algorithms] == | |||
* [http://www.cplusplus.com/reference/algorithm/ cplusplus.com] | * [http://www.cplusplus.com/reference/algorithm/ cplusplus.com] | ||
* [http://en.cppreference.com/w/cpp/algorithm cppreference.com] | * [http://en.cppreference.com/w/cpp/algorithm cppreference.com] | ||
Line 4,773: | Line 4,864: | ||
</syntaxhighlight> | </syntaxhighlight> | ||
=== all_of/ any_of/ none_of/ for_each === | |||
* http://www.cplusplus.com/reference/algorithm/all_of/ | * http://www.cplusplus.com/reference/algorithm/all_of/ | ||
* http://www.cplusplus.com/reference/algorithm/any_of/ | * http://www.cplusplus.com/reference/algorithm/any_of/ | ||
Line 4,779: | Line 4,870: | ||
* http://www.cplusplus.com/reference/algorithm/for_each/ | * http://www.cplusplus.com/reference/algorithm/for_each/ | ||
=== count/ count_if/ find/ find_if/ mismatch/ search/ search_n === | |||
'''N.B.''' | '''N.B.''' | ||
Line 4,888: | Line 4,979: | ||
</pre> | </pre> | ||
=== copy/ copy_if/ swap/ swap_ranges/ remove/ remove_if/ fill/ replace/ replace_if/ shuffle/ unique/ transform === | |||
The [http://www.cplusplus.com/reference/algorithm/transform/ transform()] function is similar to the [http://www.cplusplus.com/reference/algorithm/for_each/ for_each()] function. | The [http://www.cplusplus.com/reference/algorithm/transform/ transform()] function is similar to the [http://www.cplusplus.com/reference/algorithm/for_each/ for_each()] function. | ||
Line 4,911: | Line 5,002: | ||
Examples of '''remove_copy_if()''' and '''remove_if()''' can be found in 6.3.1 of Accelerated C++. | Examples of '''remove_copy_if()''' and '''remove_if()''' can be found in 6.3.1 of Accelerated C++. | ||
=== sort/ stable_sort/ is_sorted/ partial_sort === | |||
=== merge/ set_difference/ set_intersection/ set_union === | |||
=== max/ max_element/ min/ min_element/ next_permutation === | |||
=== accumulate/ inner_product/ partial_sum === | |||
== iterator & sequence == | |||
<pre> | <pre> | ||
Container ------- Iterator -------- Algorithm | Container ------- Iterator -------- Algorithm | ||
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</pre> | </pre> | ||
=== Using iterators in string type === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
auto b=v.begin(), e=v.end(); | auto b=v.begin(), e=v.end(); | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Using iterator in vector type === | |||
<syntaxhighlight lang='cpp'> | <syntaxhighlight lang='cpp'> | ||
vector<int>::iterator it; // it can read and write vector<int> elements | vector<int>::iterator it; // it can read and write vector<int> elements | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Examples === | |||
* [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter06/split.cc split()] function (and [http://www.cplusplus.com/reference/algorithm/find_if/ find_if()] library function) in 6.1.1 of Accelerated C++ where the '''find_if()''' function is used to find the position of non-space characters (an auxiliary function). Compare with the [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter05/split.cc split()] function in Chapter 5 where the search of a new word is done by searching the space key in a while() loop. | * [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter06/split.cc split()] function (and [http://www.cplusplus.com/reference/algorithm/find_if/ find_if()] library function) in 6.1.1 of Accelerated C++ where the '''find_if()''' function is used to find the position of non-space characters (an auxiliary function). Compare with the [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter05/split.cc split()] function in Chapter 5 where the search of a new word is done by searching the space key in a while() loop. | ||
* [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter06/urls.cc find_urls()] function in 6.1.3 of Accelerated C++ | * [https://github.com/arraytools/C/blob/master/accelerated_unix/chapter06/urls.cc find_urls()] function in 6.1.3 of Accelerated C++ | ||
== numeric == | |||
== string == | |||
== utilities == | |||
=== Function objects === | |||
=== pair === | |||
= Common errors = | |||
== array out of bound error & memory == | |||
* [https://stackoverflow.com/questions/671703/array-index-out-of-bound-in-c Array index out of bound in C] | * [https://stackoverflow.com/questions/671703/array-index-out-of-bound-in-c Array index out of bound in C] | ||
* [https://stackoverflow.com/questions/9154115/how-to-set-memory-use-limit-when-writing-c-program-and-what-happens-if-once-it-e How to set memory use limit when writing C program and what happens if once it exceeds this limit?] | * [https://stackoverflow.com/questions/9154115/how-to-set-memory-use-limit-when-writing-c-program-and-what-happens-if-once-it-e How to set memory use limit when writing C program and what happens if once it exceeds this limit?] | ||
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* [https://ss64.com/bash/ulimit.html ulimit keys] | * [https://ss64.com/bash/ulimit.html ulimit keys] | ||
== bad_alloc error == | |||
http://stackoverflow.com/questions/6833143/how-to-check-memory-allocation-failures-with-new-operator | http://stackoverflow.com/questions/6833143/how-to-check-memory-allocation-failures-with-new-operator | ||
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</pre> | </pre> | ||
= Debugging = | |||
* http://beej.us/guide/bggdb/ | * http://beej.us/guide/bggdb/ | ||
* An article from [http://www.drdobbs.com/testing/13-linux-debuggers-for-c-reviewed/240156817 Dr. Dobb's] | * An article from [http://www.drdobbs.com/testing/13-linux-debuggers-for-c-reviewed/240156817 Dr. Dobb's] | ||
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* [https://msdn.microsoft.com/en-us/library/windows/hardware/ff551063(v=vs.85).aspx Debugging Tools for Windows (WinDbg, KD, CDB, NTSD)] | * [https://msdn.microsoft.com/en-us/library/windows/hardware/ff551063(v=vs.85).aspx Debugging Tools for Windows (WinDbg, KD, CDB, NTSD)] | ||
== valgrind == | |||
http://valgrind.org/docs/manual/quick-start.html | http://valgrind.org/docs/manual/quick-start.html | ||
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</pre> | </pre> | ||
== GDB, DDD, Nemiver == | |||
* http://beej.us/guide/bggdb/ | * http://beej.us/guide/bggdb/ | ||
* http://calcul.math.cnrs.fr/Documents/Ecoles/PF-2011/Cours/debug_autrans2011.pdf | * http://calcul.math.cnrs.fr/Documents/Ecoles/PF-2011/Cours/debug_autrans2011.pdf | ||
* http://stackoverflow.com/questions/79023/is-there-a-c-gdb-gui-for-linux | * http://stackoverflow.com/questions/79023/is-there-a-c-gdb-gui-for-linux | ||
=== gdb === | |||
* http://beej.us/guide/bggdb/ mentioned gdb has a built-in ''GUI'' mode called [https://sourceware.org/gdb/onlinedocs/gdb/TUI.html '''Text User Interface''']. | * http://beej.us/guide/bggdb/ mentioned gdb has a built-in ''GUI'' mode called [https://sourceware.org/gdb/onlinedocs/gdb/TUI.html '''Text User Interface''']. | ||
* https://en.wikipedia.org/wiki/GNU_Debugger | * https://en.wikipedia.org/wiki/GNU_Debugger | ||
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|} | |} | ||
=== ddd === | |||
* [http://knuth.luther.edu/~leekent/tutorials/ddd.html A Brief Introduction to DDD] by knuth.luther.edu. | * [http://knuth.luther.edu/~leekent/tutorials/ddd.html A Brief Introduction to DDD] by knuth.luther.edu. | ||
* To use command line argument, go to Program -> Run where you can specify your command line arguments. | * To use command line argument, go to Program -> Run where you can specify your command line arguments. | ||
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</pre> | </pre> | ||
=== nemiver === | |||
Nemiver is an on going effort to write an easy to use standalone C/C++ debugger that integrates well in the GNOME environment. | Nemiver is an on going effort to write an easy to use standalone C/C++ debugger that integrates well in the GNOME environment. | ||
<pre> | <pre> | ||
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* Qt Creator. See the above discussion link for an instruction. | * Qt Creator. See the above discussion link for an instruction. | ||
== Qt Creator == | |||
A screenshot based on Qt Creator 3.3 and Qt 5.4. | A screenshot based on Qt Creator 3.3 and Qt 5.4. | ||
[[File:QtCreatorDebug.png|200px]] | [[File:QtCreatorDebug.png|200px]] | ||
== Write a Linux Debugger == | |||
https://blog.tartanllama.xyz/c++/2017/06/19/writing-a-linux-debugger-source-break/ | https://blog.tartanllama.xyz/c++/2017/06/19/writing-a-linux-debugger-source-break/ | ||
= Tools = | |||
== Online compilers == | |||
* https://wandbox.org for GCC | * https://wandbox.org for GCC | ||
* http://webcompiler.cloudapp.net/ for VC++ | * http://webcompiler.cloudapp.net/ for VC++ | ||
== IDE editor == | |||
=== [http://www.geany.org/ Geany] === | |||
Pros: show a list of symbols/functions on the left hand side panel. Show the open files as a tree structure on the left hand side. Code folding. Con: [http://plugins.geany.org/debugger.html the GDB debugger?] To install the latest version of geany and geany-plugin-debugger: | Pros: show a list of symbols/functions on the left hand side panel. Show the open files as a tree structure on the left hand side. Code folding. Con: [http://plugins.geany.org/debugger.html the GDB debugger?] To install the latest version of geany and geany-plugin-debugger: | ||
<pre> | <pre> | ||
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</pre> | </pre> | ||
=== [http://www.codeblocks.org/ Code::Blocks] === | |||
* http://wiki.codeblocks.org/index.php/Main_Page | * http://wiki.codeblocks.org/index.php/Main_Page | ||
* http://wiki.codeblocks.org/index.php/Debugging_with_Code::Blocks | * http://wiki.codeblocks.org/index.php/Debugging_with_Code::Blocks | ||
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The only thing I want to change is the font of the execution terminal. The font is too small. | The only thing I want to change is the font of the execution terminal. The font is too small. | ||
=== Qt Creator === | |||
I haven't found a way to use own Makefile to run debugging. | I haven't found a way to use own Makefile to run debugging. | ||
== GCC == | |||
[http://www.network-theory.co.uk/docs/gccintro/ Introduction to GCC] | [http://www.network-theory.co.uk/docs/gccintro/ Introduction to GCC] | ||
=== Creating shared libraries === | |||
http://www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html | * http://www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html | ||
* [https://opensource.com/article/21/2/linux-software-libraries A guide to understanding Linux software libraries in C]. | |||
** Static versus dynamic libraries. | |||
** Building the libraries. | |||
** A C library client. | |||
** Wrapping up with a Python client. | |||
=== Show all libraries used (dynamically linked) by an executable program === | |||
Use '''ldd''' ('''L'''ist '''D'''ynamic '''D'''ependencies) command on Linux environment. On Windows OS, we can use [http://dependencywalker.com/ Dependency Walker]; see [http://stackoverflow.com/questions/1993673/what-is-the-equivalent-of-linuxs-ldd-on-windows this post]. | Use '''ldd''' ('''L'''ist '''D'''ynamic '''D'''ependencies) command on Linux environment. On Windows OS, we can use [http://dependencywalker.com/ Dependency Walker]; see [http://stackoverflow.com/questions/1993673/what-is-the-equivalent-of-linuxs-ldd-on-windows this post]. | ||
* http://www.cyberciti.biz/tips/linux-shared-library-management.html | * http://www.cyberciti.biz/tips/linux-shared-library-management.html | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
=== Linking with external libraries === | |||
<pre> | <pre> | ||
$ gcc -Wall calc.c /usr/lib/libm.a -o calc | $ gcc -Wall calc.c /usr/lib/libm.a -o calc | ||
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When shared libraries are present in nondefault directories, the option "-Wl,-rpath" is needed in linker options. See [http://gcc.gnu.org/ml/gcc-help/2005-12/msg00017.html here]. If we don't specify "-Wl,-rpath" in linker options, we need to define "LD_LIBRARY_PATH" environment variable. See an example in [[R#RInside:_Embed_R_in_C.2B.2B|RInside]]. | When shared libraries are present in nondefault directories, the option "-Wl,-rpath" is needed in linker options. See [http://gcc.gnu.org/ml/gcc-help/2005-12/msg00017.html here]. If we don't specify "-Wl,-rpath" in linker options, we need to define "LD_LIBRARY_PATH" environment variable. See an example in [[R#RInside:_Embed_R_in_C.2B.2B|RInside]]. | ||
=== Header files/Include path === | |||
The list of directories for '''header''' files is often referred to as the '''include''' path, and the list of directories for '''libraries''' as the '''library''' search path or '''link''' path. | The list of directories for '''header''' files is often referred to as the '''include''' path, and the list of directories for '''libraries''' as the '''library''' search path or '''link''' path. | ||
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---- | ---- | ||
=== Environment variables === | |||
We can use some environment variables to replace '''-I''' and '''-L''' flags. See some basic introduction on | We can use some environment variables to replace '''-I''' and '''-L''' flags. See some basic introduction on | ||
* http://www.ntu.edu.sg/home/ehchua/programming/cpp/gcc_make.html | * http://www.ntu.edu.sg/home/ehchua/programming/cpp/gcc_make.html | ||
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</pre> | </pre> | ||
== Makefile == | |||
This is an example of <Makefile>. The source code files are Parent.cpp, Parent.h, Child.cpp, Child.h, and main.cpp. Remember the indents should be a single tab. | This is an example of <Makefile>. The source code files are Parent.cpp, Parent.h, Child.cpp, Child.h, and main.cpp. Remember the indents should be a single tab. | ||
<pre> | <pre> | ||
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$(CC) -c $(INCFLAGS) $< | $(CC) -c $(INCFLAGS) $< | ||
</pre> | </pre> | ||
=== 'all' and '.PHONY' targets === | |||
* (all) http://stackoverflow.com/questions/2514903/makefile-what-does-all-stand-for | * (all) http://stackoverflow.com/questions/2514903/makefile-what-does-all-stand-for | ||
* (.PHONY) http://stackoverflow.com/questions/2145590/what-is-the-purpose-of-phony-in-a-makefile. It means the target is NOT a file name. | * (.PHONY) http://stackoverflow.com/questions/2145590/what-is-the-purpose-of-phony-in-a-makefile. It means the target is NOT a file name. | ||
=== minimal make === | |||
http://kbroman.org/minimal_make/ | http://kbroman.org/minimal_make/ | ||
==== [http://www.cmake.org/ | == Autotools == | ||
* [https://www.ghacks.net/2017/05/24/how-to-build-from-source-code-in-gnulinux/ How to build from source code in GNU/Linux] | |||
* http://stackoverflow.com/questions/2531827/what-are-makefile-am-and-makefile-in | |||
'''Makefile.am''' is a programmer-defined file and is used by '''automake''' to generate the '''Makefile.in''' file. The '''./configure''' script typically seen in source tarballs will use the Makefile.in to generate a Makefile. | |||
The '''./configure''' script itself is generated from a programmer-defined file named either '''configure.ac''' or '''configure.in''' , I prefer .ac (for AutoConf) since it differentiates it from the generated Makefile.in files and that way I can have rules such as make dist-clean which rm -f *.in . Since it is a generated file it is not typically stored in a revision system such as SVN or CVS, rather the .ac file would be. | |||
Read more on [http://en.wikipedia.org/wiki/GNU_build_system GNU build system/Autotools]. Read about make and Makefile first, then learn about automake, autoconf, libtool, etc. | |||
== [http://www.cmake.org/ CMake] == | |||
[https://opensource.com/article/21/5/cmake Drop Autotools for CMake] | |||
On Windows, it will be installed on ''C:\Program Files (x86)\Cmake 2.8'' folder. By default, it is not added to system PATH. The 'Cmake' program will ask for source, binary folders and the Compiler option. After clicking 'configure' and 'generate' buttons, it will create VS solution file and we can double click the solution file to open the project in Visual Studio. In Visual Studio, we can just build the solution (Ctrl + Shift + B). When we want to debug the code, we should 1. right click on project and select property. Change the working directory to the source code (note that .exe file will be generated there). 2. Set the project as the starting project. | On Windows, it will be installed on ''C:\Program Files (x86)\Cmake 2.8'' folder. By default, it is not added to system PATH. The 'Cmake' program will ask for source, binary folders and the Compiler option. After clicking 'configure' and 'generate' buttons, it will create VS solution file and we can double click the solution file to open the project in Visual Studio. In Visual Studio, we can just build the solution (Ctrl + Shift + B). When we want to debug the code, we should 1. right click on project and select property. Change the working directory to the source code (note that .exe file will be generated there). 2. Set the project as the starting project. | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
== Profiling == | |||
* [https://www.howtoforge.com/tutorial/how-to-install-and-use-profiling-tool-gprof/ How to install and use profiling tool Gprof] | * [https://www.howtoforge.com/tutorial/how-to-install-and-use-profiling-tool-gprof/ How to install and use profiling tool Gprof] | ||
== [http://llvm.org/ LLVM] Compiler Infrastructure and Clang compiler == | |||
[http://clang.llvm.org/ clang]: a C language family frontend for LLVM | * [http://clang.llvm.org/ clang]: a C language family frontend for LLVM | ||
* [https://www.makeuseof.com/how-to-install-c-compiler-linux/ How to Install a C Compiler on Linux] | |||
= C++ Libraries = | |||
* See [http://www.richelbilderbeek.nl/Cpp.htm Richel Bilderbeek] page for more listing. | * See [http://www.richelbilderbeek.nl/Cpp.htm Richel Bilderbeek] page for more listing. | ||
== [https://computing.llnl.gov/tutorials/pthreads/ pthreads - POSIX Threads Programming] == | |||
* [http://compression.ca/pbzip2/ pbzip2] - a parallel implementation of the bzip2 block-sorting file compressor that uses pthreads and achieves near-linear speedup on SMP machines. | * [http://compression.ca/pbzip2/ pbzip2] - a parallel implementation of the bzip2 block-sorting file compressor that uses pthreads and achieves near-linear speedup on SMP machines. | ||
* [http://bowtie-bio.sourceforge.net/manual.shtml#building-from-source bowtie software] which makes use of pthread library. Similar [https://ccb.jhu.edu/software/tophat/manual.shtml tophat] and [http://cole-trapnell-lab.github.io/cufflinks/cuffmerge/index.html cuffmerge] also have a '-p' argument to support pthread. | * [http://bowtie-bio.sourceforge.net/manual.shtml#building-from-source bowtie software] which makes use of pthread library. Similar [https://ccb.jhu.edu/software/tophat/manual.shtml tophat] and [http://cole-trapnell-lab.github.io/cufflinks/cuffmerge/index.html cuffmerge] also have a '-p' argument to support pthread. | ||
== [http://www.webtoolkit.eu/wt Wt] == | |||
C++ library for developing web applications | C++ library for developing web applications | ||
== [http://trac.seqan.de/ SeqAn] == | |||
C++ for sequencing data. On Windows OS, it requires Python 2 and CMake in addition to VS. | C++ for sequencing data. On Windows OS, it requires Python 2 and CMake in addition to VS. | ||
== [http://www.boost.org/ Boost] == | |||
Boost is a set of C++ libraries for numerical computation that provide support for tasks and structures such as linear algebra, pseudorandom number generation, multithreading, image processing, regular expressions, and unit testing. Release 1.52 contains over eighty individual libraries. | Boost is a set of C++ libraries for numerical computation that provide support for tasks and structures such as linear algebra, pseudorandom number generation, multithreading, image processing, regular expressions, and unit testing. Release 1.52 contains over eighty individual libraries. | ||
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</pre> | </pre> | ||
=== build under Ubuntu OS === | |||
To install via apt-get is 'sudo apt-get install libboost-all-dev'. The software center shows the version is 1.48 (kind of old) on Ubuntu 12.04 and 1.54 on Ubuntu 14.04. | To install via apt-get is 'sudo apt-get install libboost-all-dev'. The software center shows the version is 1.48 (kind of old) on Ubuntu 12.04 and 1.54 on Ubuntu 14.04. | ||
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Running ./b2 took about 1 hours on my single core VM. At the end, it will create /usr/local/include/boost subdirectory and a bunch of libboost*.a and libboost*.so will be created under /usr/local/lib directory. | Running ./b2 took about 1 hours on my single core VM. At the end, it will create /usr/local/include/boost subdirectory and a bunch of libboost*.a and libboost*.so will be created under /usr/local/lib directory. | ||
=== Check BOOST version === | |||
* On Ubuntu, use ' tail /usr/include/boost/version.hpp' | * On Ubuntu, use ' tail /usr/include/boost/version.hpp' | ||
* IN boost C++ code, use boost version macro 'BOOST_LIB_VERSION' | * IN boost C++ code, use boost version macro 'BOOST_LIB_VERSION' | ||
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</pre> | </pre> | ||
=== Build boost from source on Windows OS === | |||
* http://andres.jaimes.net/718/how-to-install-the-c-boost-libraries-on-windows/ | * http://andres.jaimes.net/718/how-to-install-the-c-boost-libraries-on-windows/ | ||
* http://www.rodneybeede.com/Boost_C___libraries_on_Windows_with_MinGW.html | * http://www.rodneybeede.com/Boost_C___libraries_on_Windows_with_MinGW.html | ||
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</pre> | </pre> | ||
=== use of statistical distributions in Boost === | |||
See an article in [https://www.quantnet.com/threads/c-statistical-distributions-in-boost.10016/ www.quantnet.com] | See an article in [https://www.quantnet.com/threads/c-statistical-distributions-in-boost.10016/ www.quantnet.com] | ||
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Googling shows we can use '''g++ --print-search-dirs''' to show LIBRARY search paths and adding '''-v''' to show include search paths to g++ command. | Googling shows we can use '''g++ --print-search-dirs''' to show LIBRARY search paths and adding '''-v''' to show include search paths to g++ command. | ||
=== Boost thread example === | |||
http://ashishgrover.com/boost-multi-threadingfor-c/ | http://ashishgrover.com/boost-multi-threadingfor-c/ | ||
<pre> | <pre> | ||
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Another excellent example is from Jeff Benshetler. Check out this page http://advancedcplusplus.com/5min-threads/ (I cannot build it successfully). | Another excellent example is from Jeff Benshetler. Check out this page http://advancedcplusplus.com/5min-threads/ (I cannot build it successfully). | ||
=== Books === | |||
* The Boost C++ Libraries by Boris Schäling [http://en.highscore.de/cpp/boost/ Online ebook] from an old version of the book and [http://www.amazon.com/The-Boost-Libraries-Boris-Sch%C3%A4ling/dp/0982219199/ref=pd_sim_b_4 Amazon] | * The Boost C++ Libraries by Boris Schäling [http://en.highscore.de/cpp/boost/ Online ebook] from an old version of the book and [http://www.amazon.com/The-Boost-Libraries-Boris-Sch%C3%A4ling/dp/0982219199/ref=pd_sim_b_4 Amazon] | ||
* [https://www.packtpub.com/application-development/boost-c-application-development-cookbook Boost C++ Application Development Cookbook] | * [https://www.packtpub.com/application-development/boost-c-application-development-cookbook Boost C++ Application Development Cookbook] | ||
=== Boost and Rcpp package === | |||
* http://gallery.rcpp.org/articles/a-first-boost-example/ | * http://gallery.rcpp.org/articles/a-first-boost-example/ | ||
* [http://cran.r-project.org/web/packages/BH/index.html BH] package | * [http://cran.r-project.org/web/packages/BH/index.html BH] package | ||
=== [http://www.boost.org/doc/libs/1_55_0/libs/python/doc/index.html Boost.python] === | |||
http://edyfox.codecarver.org/html/boost_python.html | http://edyfox.codecarver.org/html/boost_python.html | ||
Rcpp was inspired by Boost.python. See the [http://cran.r-project.org/web/packages/Rcpp/vignettes/Rcpp-modules.pdf Rcpp module] vignette. | Rcpp was inspired by Boost.python. See the [http://cran.r-project.org/web/packages/Rcpp/vignettes/Rcpp-modules.pdf Rcpp module] vignette. | ||
== [http://scythe.wustl.edu/ The Scythe Statistical Library] == | |||
[http://www.jstatsoft.org/v42/i12 Scythe: An Open Source C++ Library for Statistical Computation] from J of Stat Software. | [http://www.jstatsoft.org/v42/i12 Scythe: An Open Source C++ Library for Statistical Computation] from J of Stat Software. | ||
== [http://arma.sourceforge.net/ Armadillo] == | |||
Armadillo is a C++ linear algebra library (matrix maths) aiming towards a good balance between speed and ease of use. | Armadillo is a C++ linear algebra library (matrix maths) aiming towards a good balance between speed and ease of use. | ||
== GNU Scientific Library == | |||
== BLAS, LAPACK == | |||
== IMSL == | |||
== Numerical Recipes == | |||
= Some C++ Projects = | |||
[https://github.com/trending/c++ Trending in Github] | [https://github.com/trending/c++ Trending in Github] | ||
== [http://www.cs.umd.edu/~mount/ANN/ Approximate nearest neighbor search] == | |||
The R wrap is [http://cran.r-project.org/web/packages/RANN/index.html here] | The R wrap is [http://cran.r-project.org/web/packages/RANN/index.html here] | ||
== BEDTools == | |||
https://github.com/arq5x/bedtools2 | https://github.com/arq5x/bedtools2 | ||
== freebayes == | |||
https://github.com/ekg/freebayes/ | https://github.com/ekg/freebayes/ | ||
== [https://github.com/NGS-lib/NGSplusplus NGS++] == | |||
A programming library in C++11 specialized in manipulating both next-generation sequencing (NGS) datasets and genomic information files. See the [http://bioinformatics.oxfordjournals.org/content/29/15/1893.short?rss=1 paper]. | A programming library in C++11 specialized in manipulating both next-generation sequencing (NGS) datasets and genomic information files. See the [http://bioinformatics.oxfordjournals.org/content/29/15/1893.short?rss=1 paper]. | ||
== [http://www.csie.ntu.edu.tw/~cjlin/libsvm/ LIBSVM] == | |||
== SAMTools (in C only) == | |||
* http://www.htslib.org/ | * http://www.htslib.org/ | ||
* https://github.com/samtools/ (new) | * https://github.com/samtools/ (new) | ||
* http://samtools.sourceforge.net/ (old) | * http://samtools.sourceforge.net/ (old) | ||
== [http://tophat.cbcb.umd.edu/tutorial.shtml Tophat] == | |||
It also requires the packages | It also requires the packages | ||
* Boost | * Boost | ||
* [http://samtools.sourceforge.net/ SamTools] and its [https://github.com/samtools/samtools source code] | * [http://samtools.sourceforge.net/ SamTools] and its [https://github.com/samtools/samtools source code] | ||
== [https://github.com/COMBINE-lab/Salmon Salmon - fast and bias-aware quantification of transcript expression] == | |||
http://www.rna-seqblog.com/salmon-fast-and-bias-aware-quantification-of-transcript-expression/ | http://www.rna-seqblog.com/salmon-fast-and-bias-aware-quantification-of-transcript-expression/ | ||
== [http://www.cs.cmu.edu/~ckingsf/software/parana2/ Parana2] == | |||
It also depends on a few other tools. | It also depends on a few other tools. | ||
* Bio++ - a set of C++ libraries for Bioinformatics, including sequence analysis, phylogenetics, molecular evolution and population genetics. | * Bio++ - a set of C++ libraries for Bioinformatics, including sequence analysis, phylogenetics, molecular evolution and population genetics. | ||
Line 5,704: | Line 5,803: | ||
* pugixml - light-weight C++ XML processing library. | * pugixml - light-weight C++ XML processing library. | ||
== [http://csse.szu.edu.cn/staff/zhuzx/CompMap/ Comprehensive short read mapping] == | |||
== [http://viq854.github.io/bwbble Short read alignment with populations of genomes] == | |||
https://github.com/viq854/bwbble | https://github.com/viq854/bwbble | ||
== [http://www.ikmb.uni-kiel.de/janus/janus.html Janus-comprehensive tool investigating the two faces of transcription] == | |||
It depends on bamtools. | It depends on bamtools. | ||
== Rcount-simple and flexible RNA-Seq read counting == | |||
* [http://bioinformatics.oxfordjournals.org/content/31/3/436.short?rss=1 Paper] | * [http://bioinformatics.oxfordjournals.org/content/31/3/436.short?rss=1 Paper] | ||
* https://github.com/MWSchmid/Rcount (based on C++ and Qt) | * https://github.com/MWSchmid/Rcount (based on C++ and Qt) | ||
== RSEM/RNA-Seq by Expectation-Maximization == | |||
* http://deweylab.biostat.wisc.edu/rsem/ | * http://deweylab.biostat.wisc.edu/rsem/ | ||
* https://github.com/bli25wisc/RSEM | * https://github.com/bli25wisc/RSEM | ||
== [http://sysbio.uni-ulm.de/soft/RNA-Pareto/ RNA-Pareto] == | |||
Interactive Analysis of Pareto-optimal RNA Sequence-Structure Alignments | Interactive Analysis of Pareto-optimal RNA Sequence-Structure Alignments | ||
The software is written in Java 6 (graphical user interface) and C++ (dynamic programming algorithms). To run, a Java Runtime Environment, version ≥1.6.0 is required. It is well tested with GCC 4.6. | The software is written in Java 6 (graphical user interface) and C++ (dynamic programming algorithms). To run, a Java Runtime Environment, version ≥1.6.0 is required. It is well tested with GCC 4.6. | ||
== [https://github.com/ANGSD/angsd ANGSD] == | |||
Analysis of Next Generation Sequencing Data | Analysis of Next Generation Sequencing Data | ||
== Open MS == | |||
http://open-ms.sourceforge.net/. It used external libraries such as: (i) Qt, which provides visualization and database support; (ii) Xerces for XML file parsing; (iii) libSVM, for machine learning algorithms; and (iv) the GNU Scientific Library (GSL), used for mathematical and statistical analysis. One of the strong points of OpenMS is a complete set of examples to extend and use the libraries, the TOPP (The OpenMS Proteomics Pipeline) and TOPPView tutorials describe in detail the OpenMS. | http://open-ms.sourceforge.net/. It used external libraries such as: (i) Qt, which provides visualization and database support; (ii) Xerces for XML file parsing; (iii) libSVM, for machine learning algorithms; and (iv) the GNU Scientific Library (GSL), used for mathematical and statistical analysis. One of the strong points of OpenMS is a complete set of examples to extend and use the libraries, the TOPP (The OpenMS Proteomics Pipeline) and TOPPView tutorials describe in detail the OpenMS. | ||
== MACAU - Differential Expression Analysis for RNAseq using Poisson Mixed Models == | |||
http://www.xzlab.org/software.html. GSL and Lapack are used. | http://www.xzlab.org/software.html. GSL and Lapack are used. | ||
= GUI Programming = | |||
== Windows Programming == | |||
=== Resource === | |||
* http://www.stanford.edu/class/cs193w/ | * http://www.stanford.edu/class/cs193w/ | ||
* [http://www.charlespetzold.com/books.html Petzold Programming Windows 1998] with source code for download | * [http://www.charlespetzold.com/books.html Petzold Programming Windows 1998] with source code for download | ||
Line 5,745: | Line 5,844: | ||
* [http://www.youtube.com/watch?v=-SXdzxWngPg Simple GUI calculator using VS C++/CLR] | * [http://www.youtube.com/watch?v=-SXdzxWngPg Simple GUI calculator using VS C++/CLR] | ||
=== Difference between Win32 project and CLR (common language runtime) project === | |||
See [http://stackoverflow.com/questions/3739392/what-is-the-difference-between-a-win32-project-clr-empty-project-and-empt here]. | See [http://stackoverflow.com/questions/3739392/what-is-the-difference-between-a-win32-project-clr-empty-project-and-empt here]. | ||
Line 5,758: | Line 5,857: | ||
''The CLR is Microsoft's implementation of the Common Language Infrastructure (CLI) standard.'' | ''The CLR is Microsoft's implementation of the Common Language Infrastructure (CLI) standard.'' | ||
=== Difference between Win32, MFC and .NET === | |||
http://stackoverflow.com/questions/821676/how-do-i-decide-whether-to-use-atl-mfc-win32-or-clr-for-a-new-c-project | http://stackoverflow.com/questions/821676/how-do-i-decide-whether-to-use-atl-mfc-win32-or-clr-for-a-new-c-project | ||
Line 5,773: | Line 5,872: | ||
System.Windows.Forms (which is what I assume you meant by CLR) is completely different, but has large similarities to MFC from its basic structure. It's by far the easiest to use, but requires the .NET framework, which may or may not be a hindrance in your case. | System.Windows.Forms (which is what I assume you meant by CLR) is completely different, but has large similarities to MFC from its basic structure. It's by far the easiest to use, but requires the .NET framework, which may or may not be a hindrance in your case. | ||
=== Why not MFC === | |||
http://win32-framework.sourceforge.net/explanation.htm The website also provides an alternative software called Win32++ to replace MFC. It also provides useful links for C++ compilers, tools, tutorial and references. | http://win32-framework.sourceforge.net/explanation.htm The website also provides an alternative software called Win32++ to replace MFC. It also provides useful links for C++ compilers, tools, tutorial and references. | ||
== [[Qt]] == | |||
* [http://www.informit.com/store/c-plus-plus-gui-programming-with-qt4-9780132354165 C++ GUI Programming with Qt 4] | * [http://www.informit.com/store/c-plus-plus-gui-programming-with-qt4-9780132354165 C++ GUI Programming with Qt 4] | ||
* Qt Graphics http://qt-project.org/doc/qt-5.0/qtdoc/topics-graphics.html | * Qt Graphics http://qt-project.org/doc/qt-5.0/qtdoc/topics-graphics.html | ||
* [http://qt-project.org/doc/qt-5.0/qtopengl/2dpainting.html 2D Painting Example] QPainter and QGLWidget can be used together to display accelerated 2D graphics on supported hardware. OpenGL examples are [http://qt-project.org/doc/qt-5.0/qtopengl/examples-widgets-opengl.html here]. | * [http://qt-project.org/doc/qt-5.0/qtopengl/2dpainting.html 2D Painting Example] QPainter and QGLWidget can be used together to display accelerated 2D graphics on supported hardware. OpenGL examples are [http://qt-project.org/doc/qt-5.0/qtopengl/examples-widgets-opengl.html here]. | ||
== [http://wxwidgets.org/ wxwidgets] == | |||
Some projects: | Some projects: | ||
* [http://sourceforge.net/projects/freefilesync/ FreeFileSync] | * [http://sourceforge.net/projects/freefilesync/ FreeFileSync] | ||
== Simple OpenGL GUI == | |||
As mentioned in http://www.oppi.uef.fi/bioinformatics/forg3d/downloads.php | As mentioned in http://www.oppi.uef.fi/bioinformatics/forg3d/downloads.php | ||
= OpenGL Programming on Windows = | |||
We need to include | We need to include | ||
Line 5,805: | Line 5,904: | ||
when you copy freeglut DLLs to C:\Windows\System32 don’t copy 64 bit DLL to syswow64 this gives a freaky error 0xc000007b when running code. Don’t know what it mean, but if you have freeglut only in system32 you going to be fine. | when you copy freeglut DLLs to C:\Windows\System32 don’t copy 64 bit DLL to syswow64 this gives a freaky error 0xc000007b when running code. Don’t know what it mean, but if you have freeglut only in system32 you going to be fine. | ||
== Resource == | |||
* [Book] OpenGL Programming Guide: The Official Guide to Learning OpenGL. [http://www.glprogramming.com/red/ Online book ver 1.1] | * [Book] OpenGL Programming Guide: The Official Guide to Learning OpenGL. [http://www.glprogramming.com/red/ Online book ver 1.1] | ||
Line 5,820: | Line 5,919: | ||
* Google: windows opengl programming tutorial visual studio | * Google: windows opengl programming tutorial visual studio | ||
== Example 1 == | |||
http://openglbook.com/setting-up-opengl-glew-and-freeglut-in-visual-c/ | http://openglbook.com/setting-up-opengl-glew-and-freeglut-in-visual-c/ | ||
Line 5,831: | Line 5,930: | ||
I keep a copy of the instruction in Evernote. | I keep a copy of the instruction in Evernote. | ||
== Example 2 == | |||
Teapot and Glut shapes (WireTeapot, SolidTeapot, SolidCube & SolidSphere) from http://openglsamples.sourceforge.net/ | Teapot and Glut shapes (WireTeapot, SolidTeapot, SolidCube & SolidSphere) from http://openglsamples.sourceforge.net/ | ||
== Example 3 (no Glut, Windows OS only) == | |||
http://www.nullterminator.net/opengl32.html | http://www.nullterminator.net/opengl32.html | ||
== Examples from [http://www.opengl.org opengl.org] == | |||
http://www.opengl.org/sdk/docs/tutorials/ | http://www.opengl.org/sdk/docs/tutorials/ | ||
== Example of American Flag == | |||
http://www.youtube.com/watch?v=9xjBlde4Cew | http://www.youtube.com/watch?v=9xjBlde4Cew | ||
= Computer Systems = | |||
== MIPS Instruction Set == | |||
* http://www.cs.columbia.edu/~sedwards/classes/2012/3827-spring/mips-isa.pdf | * http://www.cs.columbia.edu/~sedwards/classes/2012/3827-spring/mips-isa.pdf | ||
* http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-823-computer-system-architecture-fall-2005/lecture-notes/l05_singlecycle.pdf | * http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-823-computer-system-architecture-fall-2005/lecture-notes/l05_singlecycle.pdf |
Latest revision as of 20:55, 16 May 2022
Socket Programming
- Beej's Guide to Network Programming
- Linux Socket Programming by Example by Warren Gay
- UNIX Network Programming APIs 3rd; by Richard Stevens
- UNIX Network Programming by Jim Kurose
- http://www.prasannatech.net/2008/07/socket-programming-tutorial.html Socket programming in C, pERL, Python & Java.
- http://www.slideshare.net/hominhchuc/writing-client-server-programs-in-c-writing-clientserver-programs-in-c (see slides pp 19-23 & reference p31)
- http://www.yolinux.com/TUTORIALS/Sockets.html (c++ examples)
- http://www.cs.odu.edu/~mweigle/courses/cs455-f06/lectures/2-1-ClientServer.pdf
- TCP/IP Sockets in C: Practical Guide for Programmers by Donahoo and Calvert
- Effective TCP/IP Programming: 44 Tips to Improve Your Network by Jon Snader
- http://stackoverflow.com/questions/583940/is-there-a-beginners-book-for-c-socket-programming
- http://net.pku.edu.cn/~course/cs501/2011/code/BSD_Socket.t/sockets.pdf Presentation format
- Course material from Communication Networks
- Chapter 15 of Beginning Linux Programming 4th ed by Matthew and Stones.
- Chapter 18 of UNIX Systems Programming by Robbins and Robbins.
- http://www.binarytides.com/socket-programming-c-linux-tutorial/ Nice and short tutorial for beginner.
- Introduction to network functions in C http://shoe.bocks.com/net/
- http://www.cs.gsu.edu/~sguo/slides/3320/Sockets.ppt Short introduction and my local copy
- http://www.csd.uoc.gr/~hy556/material/tutorials/cs556-3rd-tutorial.pdf Long introduction and a local copy.
- http://web.cecs.pdx.edu/~jrb/tcpip/lectures/pdfs/sockets.pdf
Terms
There are two types of address domains.
- AF_UNIX: the unix domain for two processes which share a common file system, and
- AF_INET: the Internet domain for any two hosts on the Internet.
There are two types of sockets.
- a stream socket in which characters are read in a continuous stream as if from a file or pipe, and
- a datagram socket, in which messages are read in chunks.
The two symbolic constants are SOCK_STREAM and SOCK_DGRAM.
There are two types of ports:
- well known Ports | those that rarely change overtime. For instance, servers that provide mail, file transfer, remote login,
etc.
- dynamic ports | typically used only for the life of a process. For instance, pipes can be implemented using message passing
Examples of servers:
- mail server
- login server
- file server
- web server
- streaming server
- TCP ports are used for services where you need secure and complete data transmission like emails, pictures, websites, etc.
- UDP is more commonly used for quick lookups, and single use query-reply actions like video, voice, and game streaming.
- Some common examples of TCP and UDP with their default ports:
- DNS lookup UDP 53
- FTP TCP 21
- HTTP TCP 80
- POP3 TCP 110
- Telnet TCP 23
General Idea
The steps involved in establishing a socket on the client side are as follows:
- Create a socket with the socket() system call
- Connect the socket to the address of the server using the connect() system call
- Send and receive data. There are a number of ways to do this, but the simplest is to use the read() and write() system calls.
The steps involved in establishing a socket on the server side are as follows:
- Create a socket with the socket() system call
- Bind the socket to an address using the bind() system call. For a server socket on the Internet, an address consists of a port number on the host machine.
- Listen for connections with the listen() system call
- Accept a connection with the accept() system call. This call typically blocks until a client connects with the server.
- Receive and send data by using read() and write().
Internet Hearsay
- Tools for debugging sockets applications using netstat and tcpdump GNU/Linux tools.
View all TCP sockets currently active $ netstat --tcp View all UDP sockets $ netstat --udp View all TCP sockets in the listening state $ netstat --listening View the multicast group membership information $ netstat --groups Display the list of masqueraded connections $ netstat --masquerade View statistics for each protocol $ netstat --statistics Display all traffic on the eth0 interface for the local host $ tcpdump -l -i eth0 Show all traffic on the network coming from or going to host plato $ tcpdump host plato Show all HTTP traffic for host camus $ tcpdump host camus and (port http) View traffic coming from or going to TCP port 45000 on the local host $ tcpdump tcp port 45000
Make http request via telnet
Below, we only input two lines. One is telnet linus.nci.nih.gov 80 and the other is HEAD / HTTP/1.0\n\n. Remember the one carriage character and one line feed at the end of request line. We can change the HTTP method in the 2nd input to GET /HTTP/1.0\n\n to fetch the full page. See the book HTTP: The Definitive Guide and wikipedia.
$ telnet linus.nci.nih.gov 80 Trying 137.187.182.124... Connected to ncias-p942-v-1.nci.nih.gov. Escape character is '^]'. HEAD / HTTP/1.0 HTTP/1.1 200 OK Date: Thu, 21 Mar 2013 14:47:26 GMT Server: Apache Last-Modified: Tue, 12 Mar 2013 13:52:32 GMT ETag: "302a-4d7ba99db0800" Accept-Ranges: bytes Content-Length: 12330 Connection: close Content-Type: text/html Connection closed by foreign host. $
Socket Programming Examples using C/C++/Qt
Example 1 - Linux/Unix
http://www.linuxhowtos.org/C_C++/socket.htm. The codes are saved under here.
$ gcc server.c -o server $ gcc client.c -o client $ ./server 51717 $ ./client 192.168.0.21 51717 Please enter the message: Who are you? I got your message
where 192.168.0.21 is the ip address on the server. The server side will show
Here is the message: Who are you?
If everything works correctly, the server will display your message on stdout, send an acknowledgement message to the client and terminate. The client will print the acknowledgement message from the server and then terminate.
- We can actually run the client on a different machine (eg server on my Ubuntu and client on my Windows) although we can also run both client and server on the same machine.
- Once we use the port (51717) one time, we can not use the same port to run it again??? The screen shows an error "ERROR on binding: Address already in use". The problem is we may need to wait until 4 minutes for avoiding this message. See the solution in here or SO_REUSEADDR option in setsockopt(). That is, we just need to change server.c to add the following
... int iOption = 1; // Turn on keep-alive, 0 = disables, 1 = enables ... // Immediately after the declaration of sockfd, we do if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (const char *) &iOption, sizeof(int)) == -1) { error("setsockopt"); exit(1); }
- On Windows, we can use TCPView to see which process is listening on which port, socket status. On Linux, we can use netstat -a command (it gives a long output)
mli@PhenomIIx6:~/Downloads$ sudo netstat -a | grep 51717 tcp 0 0 *:51717 *:* LISTEN
- We can choose any port number between 2000 and 65535.
- If we use 51717 port for example, the server will open that port. But once the program is finished, the port will be closed immediately. Use linux command netstat -lp --inet to check which ports are opened.
Similar examples:
- http://www.thegeekstuff.com/2011/12/c-socket-programming/. This example is similar to Example 1. The server continuously runs and sends the date and time as soon as a client connects to it. To temporarily change the time, use
sudo date +%T -s "10:13:13"
. - http://www.binarytides.com/server-client-example-c-sockets-linux/
- http://www.amparo.net/ce155/socket-ex.html More complicated example
- Print client IP address
Example 2 (in C)
http://www.prasannatech.net/2008/07/socket-programming-tutorial.html
Server side (The code is here):
$ ./tcpserver TCPServer Waiting for client on port 5000 I got a connection from (127.0.0.1 , 36123) SEND (q or Q to quit) : yes RECIEVED DATA = Got it. SEND (q or Q to quit) : how are you RECIEVED DATA = I am fine. SEND (q or Q to quit) : q q ^C $
Client side (The code is here):
$ ./tcpclient Recieved data = yes SEND (q or Q to quit) : Got it. Recieved data = how are you SEND (q or Q to quit) : I am fine.
Example 3 - Simple HTTP server
The example is modified (hear files only) from http://rosettacode.org/wiki/Hello_world/Web_server (This is a wonderful website which include creating hello world web server using different programming languages). PS. the instruction in http://mwaidyanatha.blogspot.com/2011/05/writing-simple-web-server-in-c.html is worth a look but 4 lines of creating HTML standard headlines is not successful and too complicated.
We can test the server by
- opening a browser and type http://localhost:8080. Create the file by nano testServer.c
- telnet localhost 8080
- curl -i http://localhost:8080
#include<netinet/in.h> #include<stdio.h> #include<stdlib.h> #include<sys/socket.h> #include<sys/stat.h> #include<sys/types.h> #include<unistd.h> char response[] = "HTTP/1.1 200 OK\r\n" "Content-Type: text/html; charset=UTF-8\r\n\r\n" "<html>\r\n" "<head><title>Bye-bye baby bye-bye</title>\r\n" "<style>\r\n" " body { background-color: #111 }\r\n" " h1 { font-size:4cm; text-align: center; color: black;" " text-shadow: 0 0 2mm red} \r\n" "</style></head>\r\n" "<body><h1>Goodbye, world!</h1></body></html>\r\n"; int main() { int one = 1, client_fd; struct sockaddr_in svr_addr, cli_addr; socklen_t sin_len = sizeof(cli_addr); int sock = socket(AF_INET, SOCK_STREAM, 0); if (sock < 0) err(1, "can't open socket"); setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(int)); int port = 8080; svr_addr.sin_family = AF_INET; svr_addr.sin_addr.s_addr = INADDR_ANY; svr_addr.sin_port = htons(port); if (bind(sock, (struct sockaddr *) &svr_addr, sizeof(svr_addr)) == -1) { close(sock); err(1, "Can't bind"); } listen(sock, 5); while (1) { client_fd = accept(sock, (struct sockaddr *) &cli_addr, &sin_len); printf("got connection\n"); if (client_fd == -1) { perror("Can't accept"); continue; } write(client_fd, response, sizeof(response) - 1); /*-1:'\0'*/ close(client_fd); } }
Compile and run it by gcc testServer.c; ./a.out.
Example 4 - Mimic browser request
The code is based on the post. http://codebase.eu/tutorial/linux-socket-programming-c/. My local copy of [1].
This is another similar post. http://www.binarytides.com/receive-full-data-with-recv-socket-function-in-c/ which teaches how to receive full data with recv socket function in C.
Testing tcpclient.c
The result is a program that connects to google and downloads (the first 1000 bytes of) the google homepage.
$ g++ tcpclient.cpp $ ./a.out Setting up the structs... Creating a socket... Connect()ing... send()ing message... Waiting to recieve data... 1000 bytes recieved : HTTP/1.1 200 OK Date: Wed, 20 Mar 2013 14:41:54 GMT Expires: -1 Cache-Control: private, max-age=0 Content-Type: text/html; charset=ISO-8859-1 Set-Cookie: PREF=ID=78ef359985426090:FF=0:TM=1363790513:LM=1363790514:S=UO5PtdM9ETqX6Mm_; Set-Cookie: Server: gws X-XSS-Protection: 1; mode=block X-Frame-Options: SAMEORIGIN Transfer-Encoding: chunked 8000 <!doctype html><html itemscope="itemscope" itemtype="http://schema.org/WebPage"> <head><meta content="Search the world's information, Receiving complete. Closing socket... $
Testing tcpserver.c and tcpclient2.c
Server side:
$ ./tcpserver Setting up the structs... Creating a socket... Binding socket... Listen()ing for connections... Connection accepted. Using new socketfd : 4 Waiting to recieve data... 37 bytes recieved : GET / HTTP/1.1 host: www.google.com send()ing back a message... Stopping server... $
Client side (modify tcpclient.c to use IP 127.0.0.1 and port 5556):
$ ./tcpclient2 Setting up the structs... Creating a socket... Connect()ing... send()ing message... Waiting to recieve data... 10 bytes recieved : thank you.#▒ Receiving complete. Closing socket... $
Example 5 - Windows socket (almost implies C++)
Example 6 Get image using Qt
See Chapter 14. Foundation of Qt Development. The code is on https://github.com/arraytools/Qt/tree/master/FQD/Chapter14.
Example 7 Trip planner using Qt
See Chapter 15. Networking on C++ GUI Programming Qt 4. The code is on http://taichi.selfip.net:81/lang/c/qt-book/chap15/.
Basic(s)
C++ standard
- https://isocpp.org/ Status, Current Standard, Articles, Events & Training.
- C++ Wikipedia
Cheat sheet, Tutorial, Crash course
- What – if anything – have we learned from C++? by Bjarne Stroustrup.
- https://github.com/jameshfisher/cc-cheatsheet The cheat sheet is created using LibreOffice Write (odt format) and it fits a A4 paper.
- http://www.pa.msu.edu/~duxbury/courses/phy480/Cpp_refcard.pdf or my local copy.
- How to programming C++ by Matt Mahoney. It gave more explanation like using 'const' pointer to pass large object to avoid overhead of copying.
- C++ pitfalls. It covers references, const keyword, Public, Protected and Private Labels, virtual Methods and mutable Class Members.
- STL reference by Yotam Medini.
- cppreference.com
- dev-hq.net Good explanation.
- learncpp.com Quite good w/o advertising, w/ discussions & keep update.
- C++ for C programmers
- C++ crash course for C programmers
- C++ for Statisticians with a focus on interfacing from R and R packages.
- The Definitive C++ Book Guide and List
- Introduction to Programming in C++ which is suitable for high school classes.
- Youtube channels from Bo Qian. The playlists include advanced C++, modern C++, STL, Boost library, algorithms, etc.
- https://class.coursera.org/cplusplus4c-002/lecture C++ for C Programmers
- Introduction to Computer Systems from UMD. CMSC 216 from 2016.
- http://www.makeuseof.com/tag/best-youtube-programming-tutorials/ The 17 Best YouTube Programming Tutorials (including C++)
- https://blog.tartanllama.xyz/
- Teaching Materials by Ben Langmead
Differences between C and C++
- http://cs-fundamentals.com/tech-interview/c/difference-between-c-and-cpp.php
- http://techwelkin.com/difference-between-c-and-c-plus-plus
- https://www.invensis.net/blog/it/25-key-differencesbetween-c-plus-plus/
Books for C++
The Definitive C++ Book Guide and List from the stackoverflow post.
- Bjarne Stroustrup.
- The C++ Programming Language, 4th Edition 1.2k pages (epub)
- Programming: Principles and Practice Using C++ (2nd Edition) and book website 1.2k pages (epub)
- A Tour of C++ (less than 200 pages)
- C++ Primer (2012) by Stanley B. Lippman. (epub)
- Accelerated C++: Practical Programming by Example (2000) by Andrew Koenig (epub)
- The C++ Standard Library - A Tutorial and Reference by Nicolai M. Josuttis
- Effective C++ books by Scott Meyers
- C++ Primer Plus by Stephen Prata
- Jumping into C++ by Alex Allain
- Professional C++ containing C++11 syntax, by by Marc Gregoire, Nicholas A. Solter, Scott J. Kleper
- C++ Guide Pamphlet
- C++ Cookbook: Solutions and Examples for C++ Programmers by D. Ryan Stephens
- C++ Demystified: A Self-Teaching Guide by Jeff Kent (one chapter covers Character, C-String, and C++ String Class Functions) the book does not cover too much.
- C++ Without Fear
- Absolute C++ by Walter Savitch & Kenrick Mock. Explanation is very clear. Format is excellent.
- Modern C++ Programming Cookbook by Marius Bancila (May 2017) and the source code in github
- Best sellers on C++ from Amazon.
Books for C
- Top Linux developers' recommended programming books
- MASTER C++ PROGRAMMING WITH OPEN-SOURCE BOOKS
- S Oliveira and D Stewart (2006) Writing scientific software: A guide to good style. Cambridge University Press.
- BW Kernighan and DM Ritchie (1988) The C programming language, 2nd edition. Prentice Hall, Englewood Cliffs, NJ.
- PJ Plauger (1992) The standard C library. Prentice Hall, Englewood Cliffs, NJ.
- WH Press et al. (1992) Numerical recipes in C: The art of scientific computing, 2nd edition. Cambridge University Press.
- BW Kernighan and R Pike (1999) The practice of programming. Addison-Wesley, Reading, MA.
- S Oualline (1992) C Elements of Style. M&T Books, San Mateo, CA.
- S Oualline (1997) Practical C programming, 3rd edition. O'Reilly & Associates, Sebastopol, CA.
- K Loudon (1999) Mastering algorithms with C. O'Reilly & Associates, Sebastopol, CA.
- MK Loukides et al. (1997) Programming with GNU software. O'Reilly & Associates, Sebastopol, CA.
- Derek M. Jones (2009) C Language Book/An Economic and Cultural Commentary (free pdf)
- Kenneth Reek (1998) Pointers on C
C++11 for Ubuntu 12.04
http://askubuntu.com/questions/113291/how-do-i-install-gcc-4-7
sudo add-apt-repository ppa:ubuntu-toolchain-r/test sudo apt-get update sudo apt-get install gcc-4.7 g++-4.7 # Also, don't forget to update-alternatives, as suggested here sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.6 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.6 sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.7 40 --slave /usr/bin/g++ g++ /usr/bin/g++-4.7 sudo update-alternatives --config gcc
When issuing the last command, it will ask what version of gcc to use.
First code
The simplest c/c++ code
Mentioned by the above book Exploring Beaglebone: Tools and Techniques for Building with Embedded Linux.
main() { }
Hello World
C version (compiled by gcc helloworld.c)
#include <stdio.h> int main(int argc, char *argv[]) { printf("Hello World!\n"); return 0; }
C++ version (compiled by g++ <helloworld.cpp>). Note that though gcc is installed by default but g++ is not installed by default in Ubuntu 14.04 and Linux Mint 17.3. We need to install g++ manually.
#include <iostream> #include <string> using namespace std; int main() { string name; cout << "Enter your name: "; cin >> name; cout << "\nHello, " << name << "! It's nice to meet you!"; return 0; }
Note that following the keyword cout is the insertion operator (or output stream operator) '<<' and following the keyword cin is the extraction operator (or input stream operator) '>>'. Both are public member functions in iostream class.
The angular brackets (<>) around the include filename means that it is a standard, rather than a user-defined include.
The header stdio.h is located in /usr/include/ directory and iostream header is in /usr/include/c++/4.X/iostream.
Running g++ helloworld.cpp actually involved several steps (process cpp to another cpp, created assembly code, compile assembly code, link and create an executable). See the book Exploring Beaglebone: Tools and Techniques for Building with Embedded Linux Chapter 2.3.
#include <iostream>
When you do #include <iostream> it causes a set of classes and other things to be included in your source file. For iostream, and most of the standard library headers, they place these things in a namespace named std.
So the code for #include <iostream> looks something like this:
namespace std { class cin { ... }; class cout { ... }; class cerr { ... }; class clog { ... }; ... }
namespace
#include <iostream> using namespace std; namespace foo { int value() { return 5; } } namespace bar { const double pi = 3.1416; double value() { return 2*pi; } } int main () { cout << foo::value() << '\n'; cout << bar::value() << '\n'; cout << bar::pi << '\n'; return 0; }
The std namespace --- C++ Standard Library
https://en.wikipedia.org/wiki/C%2B%2B_Standard_Library
- The C++ Standard Library is a collection of classes and functions.
- Features of the C++ Standard Library are declared within the std namespace.
- The C++ Standard Library also incorporates 18 headers of the ISO C90 C standard library ending with ".h", but their use is deprecated.[2] No other headers in the C++ Standard Library end in ".h".
In the above <helloworld.cpp> C++ program, <iostream> is one of standard headers included in the C++ Standard Library. The wikipedia page categorizes the standard headers by
- Contains: <array>, <list>, <map>, <vector>, ...
- General: <algorithm>, <utility>, ...
- Localization: <locale>, <codecvt>
- Strings: <string>, <regex>
- Streams and Input/Output: <fstream>, <iostream>, <istream>, <ostream>, <sstream>
- Language support
- Thread support library
- Numerics library
- C standard library
int main() return value
- http://stackoverflow.com/questions/204476/what-should-main-return-in-c-and-c
- http://stackoverflow.com/questions/13205941/whats-the-meaning-of-the-return-value-of-int-main-and-how-to-display-it
The return value for main should indicate how the program exited. Normal exit is generally represented by a 0 return value from main. Abnormal termination is usually signalled by a non-zero return but there is no standard for how non-zero codes are interpreted.
Main function
How to write a good C main function
Naming convension
- https://google.github.io/styleguide/cppguide.html
- For private data members, prefixed with m_ (eg. see TheMagPi-issue 23).
- What does `m_` variable prefix means?
- https://en.wikipedia.org/wiki/Hungarian_notation
- For example, the QRoundProgressBar (Qt Circular Progress Bar Widget).
Some Words about Standalone Application vs Web Application
- Users can make use of the hardware power on my own machine
- Users don't worry his/her data will be used by 3rd party
- Users don't need to worry about potential network problem
- Users don't need to worry his/her jobs need to be waited in queue
- Maintainer don't need to worry the server can be hacked (purposely or incidentally). The server has to pass some security exam before it can be opened to public.
Header/Include guard, Preprocessor
#ifndef ... #define ... #endif. See wikipedia and cplusplus.com.
Basic Arithmetic
double a = 10, b=3; cout << int (a/b) << endl; // 3 cout << int (a/b + .5) << endl; // 3 a= 11; cout << int (a/b) << endl; // 3 cout << int (a/b + .5) << endl; // 4
bool type
- http://en.cppreference.com/w/cpp/language/types (true and false)
- true vs TRUE and false vs FALSE
Data Type Ranges
type | bytes | range |
---|---|---|
int | 4 | –2,147,483,648 to 2,147,483,647 |
unsigned int | 4 | 0 to 4,294,967,295 |
long | 4 | –2,147,483,648 to 2,147,483,647 |
unsigned long | 4 | 0 to 4,294,967,295 |
long long | 8 | –9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
unsigned long long | 8 | 0 to 18,446,744,073,709,551,615 |
float | 4 | 3.4E +/- 38 (7 digits) |
double | 8 | 1.7E +/- 308 (15 digits) |
Conditional operation ? :
int main(int argc, char** argv) { // logical-OR expression ? expression : conditional-expression char* filename = argc >= 2 ? argv[1] : (char*)"input.txt"; }
Increment ++ operator
Note that ++variable is slightly faster than its alternative variable++ since the alternative needs to make a copy of itself before returning the result. (see SeqAn tutorial here)
namespace
Create Utilities Function
Don't put them in a class; just make them non-member functions at namespace scope.
// header file <utility.hpp> namespace utility { void function1(); void function2(); void function3(); template<typename T> void function4() { //function template definition should be here! } } // cpp <utility.cpp> #include "utility.hpp" namespace utility { void function1() { //code } void function2() { //code } void function3() { //code } }
Memory Management
- An Introduction to Pointers for Programmers http://www.makeuseof.com/tag/introduction-pointers-programmers/
- MIP Open Course
On page 25 of the memory management lecture note, it mentions
- If using int x; the allocation occurs on a region of memory called the stack.
- If using new int; the allocation occurs on a region of memory called the heap.
Heap is outside the scope of a given function and must be explicitly cleaned up with free. When free is called, the memory is released back to system but the pointer is not set to be null. Therefore if malloc and free are used within a loop the pointer should be set to null afterwards, to allow a test on the pointer after the next malloc call. See also
- Issue 17 of The MagPi.
- What is the default value after malloc in c?. Consider calloc() or malloc() + memset().
Access the memory allocation of variable out of scope of function will cause compilation warnings and may result in unexpected crashes. The following example appeared in the MagPi magazine. A similar example also appeared in the 10.6 (Three kinds of memory management) of Accelerated C++.
include <stdio.h> int* fun() { int i=0; /* A solution is to use 'static int i=0;' */ return &i; /* Return the memory address of i. Do not do this! */ } int main() { printf("%p\n",fun()); /* Print the memory address of i within fun() */ return 0; }
Solutions:
1. Use the 'static' keyword as in the comment of the code
2. If a pointer is assigned the address of memory on the heap inside a function, then it can be accessed afterwards. After the function call, it is still necessary to call free to release the dynamically allocated memory.
#include <stdio.h> #include <stdlib.h> int* fun() { int *i=0; i=(int*)malloc(sizeof(int)); return i; } int main() { int *p = 0; p = fun(); printf("%p\n",p); free(p); return 0; }
3. Use standard containers such as vector. See the split function in Accelerated C++ Chapter 5.
#include<vector> vector<string> split(const string& s) { vector<string> ret; ... return ret; }
As mentioned in the Stroustrup C++ Style and Technique FAQ. A vector keeps track of the memory it uses to store its elements. When a vector needs more memory for elements, it allocates more; when a vector goes out of scope, it frees that memory. Therefore, the user need not be concerned with the allocation and deallocation of memory for vector elements.
Heap vs Stack
When an object is needed within several different functions calls, it might be helpful to create it on the heap instead.
The difference between creating an object on the stack and the heap is
- Objects (eg automatic variables including ordinary local variables, local variables declared using auto, and local variables declared using register) on the stack are automatically cleaned up when they go out of scope. The advantage of the stack is the speed and book-keeping. The drawback of the stack is the data is lost once the function returns.
- Objects (eg pointers) on the heap stay in memory. It has to be explicitly deleted.
// Using stack #include <iostream> #include "Square.h" using namespace std; int main() { Square s; // Using the default constructor Square s2(3. 0, ' b' ); // Using the second constructor cout << " s.area()=" << s.area() << " , s.colour()=" << s.colour() << endl ; cout << " s2.area()=" << s2.area() << " , s2.colour()=" << s2.colour() << endl ; return 0; } // Using heap #include <iostream> #include "Square.h" using namespace std; int main() { Square *s = new Square(); // Using the default constructor Square *s2 = new Square(3. 0, ' b' ); // Using the second constructor cout << "s->area()=" << s->area() << " , s->colour()=" << s->colour() << endl ; cout << "s2->area()=" << s2->area() << " , s2->colour()=" << s2->colour() << endl ; delete s; delete s2; return 0; }
Some references:
- What could be the advantages of stack over heap dynamic memory allocation in C?
- The MagPi issue 23
- C++ Primer Plus Chapter 9.
The auto_ptr Class (deprecated as of C++11)
- See Chapter 16 of C++ Primer Plus.
- http://www.cplusplus.com/reference/memory/auto_ptr/. This class template is deprecated as of C++11. unique_ptr is a new facility with a similar functionality, but with improved security (no fake copy assignments), added features (deleters) and support for arrays.
new, delete operators, pointers and dynamic memory
Use new/delete instead of malloc()/free() which depends on <cstdlib> in C++. For example, the following code was a modification from Listing 4.22 (p169) <delete.cpp> from the book 'C++ Primer Plus'.
The memory created by new operator is called heap or free store. Forgetting to use delete operator will cause a memory leak. This kind of storage is called dynamic storage which differs from automatic storage and static storage/stack.
#include <iostream> #include <cstring> // strlen() using namespace std; int main() { char * pn = new char(strlen("/home") + strlen("/Downloads") + 1); strcpy(pn, "/home"); cout << pn << endl; cout << strlen(pn) << endl; strcat(pn, "/Downloads"); cout << pn << endl; cout << strlen(pn) << endl; delete [] pn; return 0; }
- new allows to allocate a variable length arrays while allocating arrays on the stack stack size must be constant. See p52 of MIT Open Course or p33 of TheMagPi issue 23.
- new and delete should be used together. See p62 to p67 of the above MIT note.
- Pay attention to the scope of variables. If a variable is declared within a parenthesis, it will evaporate once it exists the parenthesis. See p69 of the above MIT note for the problem and p75 for the solution.
- See Chapter 4, 9, 12 of C++ Primer Plus. Or Chapter 14 of C++ Without Fear
- When a program interacts with other programs in a GUI or network environment, it typically passes or receives pointers to objects.
scalar
int *pn = new int; // dynamic delete pn; VS int higgens; int *pt = &higgens; // not dynamic
Array
- Linux C Programming Tutorial Part 19: Pointers and Arrays from HowToForge.
- Every array contains a sequence of one or more objects of the same type. The number of elements in the array must be known at compile time, which requirement implies that arrays cannot grow or shrink dynamically the way library containers do. See 10.1.3 of Accelerated C++.
- Because arrays are not class types, they have no members. In particular, they do not have the size_type member to name an appropriate type to deal with the size of an array.
- The <cstddef> header defines size_t, which is a more general type.
const size_t NDim = 3; double coords[NDim]; static const double numbers[] = {97, 94, 90, 0 }; static const size_t ngrades = sizeof(numbers) / sizeof(*numbers);
- There is a fundamental relationship between arrays and pointers.
*coords = 1.5; // the array's initial element
int *pn = new int[10]; // OR int *pn; pn = new int[10]; pn[1] =3; delete[] pn; int *parr[40]; // array of 40 pointers to int
function
# Listing 4.22.1 <delete.cpp> from C++ Prime Plus (5th ed) char *name; char *getname(); // prototype char *getname() { char* out = new char[5]; ... return out; } name = getname(); delete [] name; # 1. It is possible to use 'new' in a function and use 'delete' in the main function. # 2. This memory is not controlled by scope. It means new & delete gives you more # power to control over how a program uses memory. # 3. See also PPP Chapter 20.1. # double* jack_data = get_from_jack(&jack_count); # vector<double>* jill_data = get_from_jill(); # //... # delete[] jack_data; # delete jill_data;
use new(delete) in a class constructor(destructor)
# Listing 12.4, 12.5 and p591-593 of C++ Primer Plus (5th ed) String::String (const String & st) { len = st.len; str = new char [len + 1]; std::strcpy(str, st.str); } String::~String() { delete [] str; }
dereference
Fraction *pFrac = new Fraction(1, 2); (*pFrac).get_num(); // OR pFrac->get_num(); (*pFrac).member; // pFrac->member;
combining dereference and increment in a single expression
auto pbeg = v.begin(); // print elements up to the first negative value while (pbeg != v.end() && *pbeg >= 0) cout << *pbeg++ << endl; // print the current value and advance pbeg
The precedence of postfix increment is higher than that of the dereference operator, so *pbeg++ is equivalent to *(pbeg++) . The operand of * is the unincremented value of pbeg. Thus, the statement prints the element to which pbeg originally pointed and increments pbeg.
variable array size in new
int n; cout << "How many elements?"; cint >> n; int *p = new int[n]; .... delete [] p;
null pointer
See Null Pointers in comp.lang.c Frequently Asked Questions.
There are several ways to create a null pointer.
int *p1 = nullptr; // C++11 int *p2 = 0; int *p3 = NULL; // must #include cstdlib header which defines the preprocessor variable NULL as 0.
Modern C++ programs generally should avoid using NULL and use nullptr instead.
To test whether a pointer is valid, we can use either
if (p0 != nullptr) // consider p0 valid
OR
if (p0) // consider p0 valid; p0 is not zero.
dealing with problems with memory allocation
If the memory requested is not available, the new operator returns a null pointer.
You can test for this possibility and take the appropriate action.
int *p = new int[1000]; if (!p) { cout << "Insufficient memory."; exit(-1); }
Memory leak
The answer is Yes.
Test memory leak
The following C++ code was used to test a memory leak and also the capacity of memory. Note that when 'n' is declared as unsigned int, the maximum value can be 4,294,967,295=2^32-1 which corresponds to 32,767 MB (about 32 GB) in size for a double vector (assume 8 bytes). If I change the type of n to "unsigned long long", its range can go up to 18,446,744,073,709,551,615=2^64-1 or 137438953472 GB in size for a double vector.
Note that the program should be built in x64 instead of win32 version in Visual Studio if we like to test it on non-Windows-XP OS on Windows. Linux OS does not need to worry...
#include <iostream> using namespace std; void foo(unsigned long long n) { double *ptr = new (std::nothrow) double[n]; if (!ptr) { cout << "Failed to allocate double[n]" << endl; } else { ptr[1] = 1.0; ptr[n-1] = 2.0; cout << "double[n] is allocated successfully!" << endl; } } int main() { cout << "The program is used to test memory leak. \n"; cout << "Do not worry. It won't crash your computer.\n"; cout << "The source code is available on https://gist.github.com/arraytools/6689581 \n" << endl; unsigned long long n; int testChoice; cout << "Enter your choice 1=main, 2=sub: "; cin >> testChoice; cout << "\nNext enter the array size (<= 18,446,744,073,709,551,615) : "; cout << "\nSome common scenarios"; cout << "\n268,435,456-1 = 2GB"; cout << "\n536,870,912-1 = 4GB"; cout << "\n1,073,741,824-1 = 8GB"; cout << "\n2,147,483,648-1 = 16GB"; cout << "\n4,294,967,296-1 = 32GB"; cout << "\n8,589,934,592-1 = 64GB"; cout << "\n"; cin >> n; if (testChoice == 1) { double *ptr = new (std::nothrow) double[n]; if (!ptr) { cout << "Failed to allocate double[n]" << endl; } else { ptr[1] = 1.0; ptr[n-1] = 2.0; cout << "double[n] is allocated successfully!" << endl; } } else { foo(n); } return 0; }
and my testing result on Windows XP with 2GB physical memory & 2GB virtual memory. The program is compiled into 32-bit console application. It is a different story when tested on 64-bit Windows 7.
Array Size | Main | Function |
---|---|---|
20,000,000 =150 MB | OK | OK |
200,000,000=1.5 GB | OK | OK |
2000,000,000=15 GB | Not OK | Not OK |
500,000,000 =4 GB | Not OK | Not OK |
250,000,000=1.91 GB | OK | OK |
270,000,000=2.06 GB | Not OK | Not OK |
Enumerations
See 2.3.3 of The C++ Programming language or http://en.cppreference.com/w/cpp/language/enum
Unscoped enumeration
enum Color { RED, GREEN, BLUE }; Color r = RED; switch(r) { case RED : std::cout << "red\n"; break; case GREEN: std::cout << "green\n"; break; case BLUE : std::cout << "blue\n"; break; }
Scoped enumerations
enum class Color { RED, GREEN = 20, BLUE }; Color r = Color::BLUE; switch(r) { case Color::RED : std::cout << "red\n"; break; case Color::GREEN: std::cout << "green\n"; break; case Color::BLUE : std::cout << "blue\n"; break; } // int n = r; // error: no scoped enum to int conversion int n = static_cast<int>(r); // OK, n = 21
this keyword/pointer
The this keyword is valid only inside a member function, where it denotes a pointer to the object on which the member function is operating. For example, inside Vec::operator=, the type of this is Vec*, because this is a pointer to the Vec object of which operator= is a member. For a binary operator, such as assignment, this is bound to the left-hand operand. Ordinarily, this is used when we need to refer to the object itself, as we do here both in the initial if test and in the return.
Communication between objects
See Pi magazine issue 24. The secret is to use this pointer to pass a pointer to the data member object. In header files,
// Child.h #ifndef CHILD_H #define CHILD_H class Parent; // forward declaration to reduce precompile time class Child { .... } #endif // Parent.h #ifndef PARENT_H #define PARENT_H class Child; // forward declaration to reduce precompile time class Parent { ... } #endif
In C++ files,
// Child.cpp Child::Child(Parent *parent): m_parent(parent) { } void Child::run() { cout << m_parent->x() << ", " << m_parent->y() << endl; } // Parent.cpp Parent::Parent(unsigned int x, unsigned int y): m_child(0), m_x(x), m_y(y) { if (!m_child) m_child = new Child(this); m_child->run(); }
C++ videos
Type casting
by declaiming explicitly like (float)5 or using suffix like 5f.
Global variables, header
http://stackoverflow.com/questions/9702053/how-to-declare-a-global-variable-in-c
1. Put extern int myvar in the header file 2. Put int myvar in the cpp file
// header file <myheader.h> extern int x // cpp file #include "myheader.h" void foo() { x = 5; }
C vs C++ with functions
In non-object programming, we use
function(x, parameter)
In C++ programming, we use
x->function(parameter) // if x is a pointer x.function(parameter) // if x is not a pointer
<cstdlib> vs <stdlib.h>
The first one is for C++ and the other is for C. See here.
Function Prototypes
For example,
void cheers(int); // prototype: no return value double cube(double x); // prototype: returns a double int main() { ... }
Functon prototyping is often hidden in the include files.
Pass function name in a function
See
- Chapter 4 of Accelerated C++. <Student_info.cc>. Well there is no functions as arguments in this case. Just want to show an opposite of write_analysis() function.
int main() { .... vector<double> homework; read_hw(cin, homework); // note that returning the stream allows our caller to write // if (read_hw(cin, homework)) { /* ... */ } // as an abbreviation for // read_hw(cin, homework); // if (cin) { /* ... */ } .... } istream& read_hw(istream& in, vector<double>& hw) { // 'in' is not copied. We will modify it and return it. .... return in; }
- Chapter 6 of Accelerated C++. The caller <grade_analysis.cc> and function <analysis.cc>.
int main() { ... write_analysis(cout, "median", median_analysis, did, didnt); write_analysis(cout, "average", average_analysis, did, didnt); ... } void write_analysis(ostream& out, const string& name, double analysis(const vector<Student_info>&), const vector<Student_info>& did, const vector<Student_info>& didnt) { out << name << ": median(did) = " << analysis(did) << ", median(didnt) = " << analysis(didnt) << endl; }
For the ostream & parameter, see Write a Function to Contain an Argument of Output Device.
Argument Passing in Functions
References as a function argument seems more popular for numerical values and Pointers as a function argument seems popular for char arrays. It is introduced in C++ Primer Chapter 6.2.2.
The argument can be a scalar or an array. Also it be numerical values or character strings.
Pointers as a function argument
The following example is coming from http://www.nongnu.org/c-prog-book/online/x641.html. See also cplusplus.com tutorial about pointers.
#include <stdio.h> int swap_ints(int *first_number, int *second_number); int main() { int a = 4, b = 7; printf("pre-swap values are: a == %d, b == %d\n", a, b); swap_ints(&a, &b); printf("post-swap values are: a == %d, b == %d\n", a, b); return 0; } int swap_ints(int *first_number, int *second_number) { int temp; temp = *first_number; *first_number = *second_number; *second_number = temp; return 0; }
Another example
#include <stdio.h> void printArray(int * arr, int size) { int i; printf("Array elements are: "); for(i = 0; i < size; i++) { arr[i] += 10; printf("%d, ", arr[i]); } } int main() { int arr[5] = {1, 2, 3, 5, 4}; printArray(arr+1, 5); // Pass array directly to function printArray return 0; } // Output: Array elements are: 12, 13, 15, 14, 32774,
References as a function argument
The new variable is called Reference Variables which is a name that acts as an alias. This is described in C++ Primer Plus Chapter 8. See also
Here we create a reference that looks and acts like a standard C++ variable except that it operates on the same data as the variable that it references.
The following example is modified from C++ pitalls.
int foo = 3; // foo == 3 int &bar = foo; // foo == 3. bar is of type int &. The ampersand & is NOT the address operator. bar = 5; // foo == 5 int * prats = &foo; // prats is a pointer. *prats and bar can be used interchangeably with foo // and use the expression &bar and prats interchangeably with &foo.
and the same concept of references is used when passing variables.
#include <iostream> using namespace std; void foo( int &i ) { i++; } int main() { int bar = 5; // bar == 5 cout << bar << endl; foo( bar ); // bar == 6 cout << bar << endl; foo( bar ); // bar == 7 cout << bar << endl; return 0; }
However, reference variable 1. it is necessary to initialize the reference when you declare it 2. a reference is rather like a const pointer; you have to initialize it when you create it and once a reference pledges its allegiance to a particular variable, it sticks to its pledge.
More examples from this post.
// OK case. main: int i=6; chgInt(&i); function: void chgInt(int *p); *p = 10 + *p; // Not OK case. main: char *name = "old"; chgStr(name); function: void chgStr(char *n); n = "new"; // This will make a new string, not changing the original one // Correction main: SAME function: void chgStr(char* &n); n = "new";
In fact, the way of using char* &n in function argument is also used by Foundation of Qt Development List 1.1 and 1.2 where string is used instead of char*. Below is the code of List 1.1:
class MyClass { public: MyClass( const string& text ); const string& text() const; void setText( const string& text ); int getLengthOfText() const; private: string m_text; };
In PPP book, Stroustrup also uses call by references everywhere, such as:
// 21.9 Container algorithms void test(vector<int>& v) { sort(v.begin(), v.end()); } int main() { vector<int> vs; test(vs); }
A real power of using references is in the example of PPP book Chapter 20.1 where we can use C' way in C++ to access a value in C++'s vector.
# C array double* jack_data = get_from_jack(&jack_count); # jack_data[i] ---- value # &jack_data[i] ---- address # C++ vector vector<double>* jill_data = get_from_jill(); # Then instead of using the basic way to access the data # (*jill_data)[i] ---- value # &(*jill_data)[i] ---- address # we can use the reference method vector<double>& v = *jill_data; # v[i] ---- value # &v[i] ---- address
Comparison of Reference and Pointer
Reference (pass by reference) | Pointer (pass by address) | |
---|---|---|
Main | int a; int & bar = a; foo(a); // pass variable (not pass address of the variable) // it 'can' be passing 'values' of variables; // determined by prototype of the function def.note: no * is used. & is used in the declaration. |
int a; int * bar = &a; foo(&a); // pass address of variablesnote: * is used in the declaration. |
Function |
foo(int &b) // b is an alias. It can be used directly. // For example, b = 10;note: no * is used. & is used in the declaration. |
foo(int *b) // b is a pointer to an int // For example, *b = 10;note * is used in the declaration. |
lvalue and rvalue
- Chapter 8.5.6 Pass-vy-value vs pass-by-reference of PPP (an easy to follow book with essential concepts there).
- Chapter 6.4 Objects and Values of The C++ Programming Language.
- Chapter 7.7.1 Lvalue References and 7.7.2 Rvalue References of The C++ Programming Language.
void g(int a, int& r, const int& cr) { ++a; ++r; int x = cr; } int main() { int x = 0; int y = 0; int z = 0; g(x, y, z); // x==0; y==1; z==0 g(1, 2, 3); // error: reference argument r needs a variable to refer to g(1, y, 3); // OK since cr is const we can pass a literal }
rvalue reference, && and Move semantics
This is used to avoid 'copy' data. The situation happened in copy constructor or assignment. It is important especially for large data.
- See Programming: Principal and Practice (2nd ed) 18.3.4. It is a new feature in C++11.
- Google it.
Pass the (address) of the pointer (char array) as function argument
#include <string.h> #include <iostream> using namespace std; void SetName( char **pszStr ) { char* pTemp = new char[10]; strcpy(pTemp,"Mark"); *pszStr = pTemp; // assign the address of the pointer to this char pointer } void SetNameBetter(char *& pszStr ) { char* pTemp = new char[10]; strcpy(pTemp,"MarkBetter"); pszStr = pTemp; // this works because pxzStr *is* the pointer in main } void SetNameNotOK( char *pszStr ) { char* pTemp = new char[10]; strcpy(pTemp,"Mark"); pszStr = pTemp; } int main(void){ char* pszName = NULL; // SetName( pszName ); SetName( &pszName ); // pass the address of this pointer so it can change cout<<"Name - "<< pszName<<endl; // not *pszName SetNameBetter( pszName ); // pass the pointer into the function, using a reference cout<<"Name - "<< pszName<<endl; // not *pszName delete [] pszName; return 0; }
Function and Arrays
(C++ Primer Ch 6.2.4 Array Parameters) Because arrays are passed as pointers, functions ordinarily don't know the size of the array they are given. There are three techniques used to manage pointer parameters
- using a marker to specify the extent of a character array (null character for C-style strings)
- using the standard library conventions (begin and end pointers) and
- explicitly passing a size parameter.
See Chapter 7 of C++ Primer Plus (5th ed).
# Version 1. int sumarray(int arr[], int n) { int total = 0; for(int i=0; i<n; i++) total += arr[i]; return total; } # Version 2. int sumarray(int * arr, int n) { int total = 0; for(int i=0; i<n; i++) total += arr[i]; // arr[i] is equivalent to *(arr + i) return total; } # Version 3a. int sumarray(const int arr[], int n); //protect input array # Version 3b. int sumarray(const int *begin, const int *end) { const int *pt; int total = 0; for(pt=begin; pt != end; pt++) total += *pt; return total; }
Pointer and const
See Chapter 7 of C++ Primer Plus (5th ed).
int sloth = 3; const int * ps = &sloth; // a pointer to const int, prevent using the pointer to change the pointed-to value int * const finger = &sloth; // a const pointer to int, prevent from changing where the pointer points.
Functions and Two-Dimensional Arrays
int data[3][4] = {{1,2,3,4}, {5,6,7,8}, {9,10,11,12}}; // data is an array with 3 elements. int total = sum(ar, 3); // Since the first element of data is an array of 4 int values. so ar should be a pointer to array-of-four-int. // What is the prototype? int sum(int (*ar)[4], int size); // the parentheses are needed because '''int *ar[4]''' should declare // an array of 4 pointers to int. OR int sum(int ar[][4], int size); int sum(int ar[][4], int size) { int total = 0; for(int r=0; r< size; r++) for(int c=0; c<4; c++) total += ar[r][c]; return total; }
Note that the parentheses around *ar are necessary:
int *matrix[10]: // array of 10 pointers int (*matrix)[10]: // pointer to an array of ten ints
command line arguments, arguments to main
int main(int argc, char *argv[]) { ... } // argv is an array of pointers to C-style character strings. int main(int argc, char **argv) { ... } // argv points to a char *. argv[0] = "prog"; // actually it is 'p', 'r', 'o', 'g', '\0'. argv[1] = "-i"; // or '-', 'i', '\0'. argv[2] = "inputfile"; argv[3] = "-o"; argv[4] = "outputfile";
Varying parameters
(C++11) initializer_list parameters.
void error_msg(initializer_list<string> i1) { for (auto beg = i1.begin(); beg != i1.end(); ++beg) cout << *beg << " "; // OR for (const auto &elem : i1) cout << elem << " "; cout << endl; } ... if (expected != actual) { error_msg({"foo", expected, actual}); else error_msg({"foo", "Okay"}); }
Ellipsis parameters
Ellipsis parameters are in C++ to allow programs to interface to C code that uses a C library facility named varargs.
void foo(param_list, ...); void foo(...);
Return a pointer to an array
See C++ Primer Ch 6.3.3.
A function cannot return an array. It can return a pointer or a reference to an array. However, the syntax used to define functions that return pointers or references to arrays can be intimidating.
(C++11) Trailing return type. Trailing returns can be defined for any function with complicated return types, such as pointers (or references) to arrays. A trailing return type follows the parameter list and is preceded by ->. To signal that the return follows the parameter list, we use auto where the return type ordinarily appears.
// fcn takes an int argument and returns a pointer to an array of 10 ints auto func(int i) -> int(*)[10];
Alternativly, if we know the array(s) to which our function can return a pointer, we can use decltype to declare the return type. For example, the following function returns a pointer to one of two arrays, depending on the value of its parameter.
int odd[] = {1, 3, 5, 7, 9}; int even[] = {2, 4, 6, 8, 10}; // returns a pointer to an array of 5 int elements decltype(odd) *arrptr(int i) { return(i % 2) ? &odd : &even; // return a pointer to the array }
Pointer, vector and element
- See PPP 20.1 (Storing and processing data) and 20.1.1 (Working with data).
// If jill_data is a pointer from get_from_jill() which returns a pointer to a vector vector<double>* get_from_jill(); vector<double>* jill_data = get_from_jill(); int i = 1; cout << *jill_data[i]; // means *(jill_data[i]) which is not we want. cout << (*jill_data[i]); // good because [ ] binds tigher than *. delete jill_data;
pass a vector of strings using reference
See how to pass a vector of strings using reference.
#include <iostream> #include <vector> #include <string> using namespace std; void foo(char* &s) { /* Goal: print an array of character s */ /* approach 1: not working. Only the first character is shown. cout << *s << " "; */ /* approach 2: simplest solution */ cout << s << " "; /* approach 3: loop. Works fine while(*s) printf("%c",*s++); */ /* approach 4: non-loop. Works fine. /* std::string str(s, s + strlen((const char *)s)); convert char* to string cout << str << " "; and then print out */ } void foo2(vector<string> vs) { // for(auto it : vs) cout << it << endl; for C++11 for (std::vector<string>::iterator it = vs.begin(); it!=vs.end(); ++it) cout << ' ' << *it; } void foo3(vector<string> &vs) { for (std::vector<string>::iterator it = vs.begin(); it!=vs.end(); ++it) cout << ' ' << *it; cout << endl; for (unsigned int i=0; i < vs.size(); ++i) cout << ' ' << vs[i]; } int main() { const int argc=4; // C style of an array of pointers to characters char** argv = new char *[argc];; argv[0] = "This"; argv[1] = "Is"; argv[2] = "A"; argv[3] = "Book"; cout << "char** type" << endl; cout << "Call directly" << endl; for(int i=0; i<argc; i++) cout << argv[i] << " "; cout << endl; cout << "Call foo()" << endl; for(int i=0; i<argc; i++) foo(argv[i]); // only 1 string at a time cout << endl << endl; // std::vector<std::string> vs = {"This", "Is", "A", "Book"}; C++11 std::vector<std::string> vs; vs.push_back("This"); vs.push_back("Is"); vs.push_back("A"); vs.push_back("Book"); cout << "string vector type" << endl; cout << "Print from main()" << endl; for (std::vector<string>::iterator it = vs.begin(); it!=vs.end(); ++it) cout << ' ' << *it; cout << endl; cout << "Call foo2() pass by value" << endl; foo2(vs); // pass whole vector cout << endl; cout << "Call foo3() pass by reference" << endl; foo3(vs); // pass whole vector cout << endl; delete[] argv; return 0; }
And the output
char** type Call directly This Is A Book Call foo() This Is A Book string vector type Print from main() This Is A Book Call foo2() pass by value This Is A Book Call foo3() pass by reference This Is A Book This Is A Book Press <RETURN> to close this window...
A similar example is to create the vector elements in subroutine and again the vector is passed by reference.
#include <iostream> #include <vector> #include <string> using namespace std; void foo(vector<string> &vs) { vs.push_back("This"); vs.push_back("Is"); vs.push_back("A"); vs.push_back("Book"); } void foo2(vector<string> &vs) { for (std::vector<string>::iterator it = vs.begin(); it!=vs.end(); ++it) cout << ' ' << *it; cout << endl; } int main() { std::vector<std::string> vs; cout << "string vector type" << endl; cout << "Print from main()" << endl; for (std::vector<string>::iterator it = vs.begin(); it!=vs.end(); ++it) cout << ' ' << *it; cout << endl; cout << "Pass by reference" << endl; foo(vs); // pass whole vector foo2(vs); return 0; }
For 2 dimensional matrix of string, see the example below.
Container class in C++ vs simple array in C
https://isocpp.org/wiki/faq/containers
try { ... } catch { ... } for exception handling
- http://msdn.microsoft.com/en-us/library/6dekhbbc(v=vs.80).aspx
- http://www.cplusplus.com/doc/tutorial/exceptions/
- http://www.dev-hq.net/c++/22--try-and-catch. It explains why we typically want to separate throw (usually defined in a function) and try-catch (usually defined in a caller function). It also shows we'd better use 'pass the exception by reference' practice. The values thrown from the function can be a numerical number, a string or a custom class.
try { throw 20; } catch (int e) { cout << "An exception occurred. Exception Nr. " << e << endl; }
Second example.
char *buf; try { buf = new char[512]; if( buf == 0 ) throw "Memory allocation failure!"; } catch( char * str ) { cout << "Exception raised: " << str << '\n'; }
Third example.
try { return grade(s); } catch (domain_error) { return grade(s.midterm, s.final, 0); }
Fourth example,
#include <iostream> using namespace std; int divide_numbers(int a, int b) { if(b==0) throw 1; return a/b; } int main() { int a, b; cout << "One: "; cin >> a; cout << "Two: "; cin >> b; try { cout << divide_numbers(a, b); } catch(int& code) { cout << "ERROR CODE: " << code; } catch(...) { cout << "An unknown error has occurred."; } //Continue doing whatever afterwards like normal return 0; }
Fifth example,
#include <iostream> using namespace std; int main() { try { int* myarray = new int[100000000000000]; delete [] myarray; } catch(exception& e) //Takes a reference to an 'exception' object { cout << "Error allocating memory: " << e.what() << endl; } }
Sixth example,
// http://www.tenouk.com/cpluscodesnippet/domainerrortypeid.html // http://www.cplusplus.com/reference/exception/exception/?kw=exception #include <iostream> #include <exception> // operator exception #include <typeinfo> // operator typeid using namespace std; int main(void) { try { throw domain_error("Some error with your domain!"); } catch (std::exception &err) { cerr<<"Caught: "<<err.what()<<endl; cerr<<"Type: "<<typeid(err).name()<<endl; }; }
Exception classes
http://www.cplusplus.com/reference/exception/exception/
- logic_error
- domain_error
- invalid_argument
- length_error
- out_of_range
- runtime_error
- range_error
- overflow_error
- underflow_error
Class
The fundamental ideas behind classes are data abstraction and encapsulation.
Data abstraction separate interface and implementation. The interface of a class consists of the operations that users of the class can execute. The implementation includes the class's data members, the bodies of the functions.
Encapsulation enforces the separation of a class' interface and implementation.
Class vs struct
The only difference between struct and class is the default access level.
Members in a class are private by default while members defined in struct are public.
A simple class (C vs Qt)
Note that a constructor is not needed.
C | Qt | |
---|---|---|
myclass.h | #include <string> using namespace std; class MyClass { public: // MyClass(); string file; string createCmd(const string & cmd); }; |
#include <QtCore> class MyClass { public: // MyClass(); QString file; QString createCmd(const QString & cmd); }; |
myclass.cpp | #include "myclass.h" //MyClass::MyClass() //{ //} string MyClass::createCmd(const string & file) { string cmd; cmd = file + file; return cmd } |
#include "myclass.h" //MyClass::MyClass() //{ //} QString MyClass::createCmd(const QString & file) { QString cmd; cmd = file + file; return cmd; } |
main.cpp | #include <iostream> #include <string> #include "myclass.h" using namespace std; int main(int argc, char *argv[]) { MyClass myclass; cout << myclass.createCmd("ABCD ") endl; } |
#include <QCoreApplication> #include <QtDebug> #include "myclass.h" int main(int argc, char *argv[]) { MyClass myclass; qDebug() << myclass.createCmd("ABCD "); } |
We can build the Cpp codes by g++ myclass.cpp main.cpp.
Single colon and double colons
Single colon
- Single colon ":" was used in inheritance. For instance,
class fourwheeler {} class car: public fourwheeler {}
- Single colon can be used in the class (constructor) member initializer list. See Defining class member functions and member initializer list or (may not be that clear example) pp49-50 of The C++ Programming Language (4th ed, Stroustrup).
class Vector { public: Vector(int s) :elem{new double(s)}, sz{s} {} double& operator[](int i) { return elem[i]; } int size() { return sz; } private: double* elem; int sz; }
Double colons
- Double colons was used to define/refer a class's function/method. Sometimes it can be used to resolve namespace problem. See here.
void MyClass::setText() {}
:: operator
The :: in the function name is the same scope operator. For example, <Student_info.cc> in Accelerated C++,
double Student_info::grade() const { return ::grade(midterm, final, homework); }
Note that the :: in front of a name insists on using a version of that name that is not a member of anything. In this case, we call the version of grade that takes two doubles and a vector<double>.
The const in is a promise that calling the grade function will not change any of the data member of the Student_info object (Accelerated C++ 9.2.1). We can understand this usage by comparing the new function declaration with the original:
double Student_info::grade() const { ... } // member-function version double grade(const Student_info&) { ... } // original
The grade() declared in Stduent_info::grade() is a const member function.
Another more explicit example is on Why does C++ need the scope resolution operator.
#include <iostream> int a = 10; namespace M { int a = 20; namespace N { int a = 30; void f() { int x = a; //a refers to the name inside N, same as M::N::a int y = M::a; //M::a refers to the name inside M int z = ::a; //::a refers to the name in the global namespace std::cout << x << ", "<< y << ", " << z << std::endl; //30,20,10 } } } int main() { M::N::f(); }
Accessor and Mutator
What is the difference between accessor and mutator methods? An accessor is a class method used to read data members, while a mutator is a class method used to change data members.
class foo { private: int a; public: int accessA() const { return(a);} void mutateA(const int A) { a = A;} }
Access Member Functions
Use "." dot for regular objects. See the next session.
For pointers to a class, use arrows "->".
Pointers to classes
// http://www.cplusplus.com/doc/tutorial/classes/ #include <iostream> using namespace std; class Rectangle { int width, height; public: Rectangle(int x, int y) : width(x), height(y) {} int area(void) { return width * height; } }; int main() { Rectangle obj (3, 4); Rectangle * foo, * bar, * baz; foo = &obj; bar = new Rectangle (5, 6); baz = new Rectangle[2] { {2,5}, {3,6} }; cout << "obj's area: " << obj.area() << '\n'; cout << "*foo's area: " << foo->area() << '\n'; cout << "*bar's area: " << bar->area() << '\n'; cout << "baz[0]'s area:" << baz[0].area() << '\n'; cout << "baz[1]'s area:" << baz[1].area() << '\n'; delete bar; delete[] baz; return 0; }
Access parent class data member
Default constructor
The default constructor is the constructor that takes no parameters. It is called when an object is declared but is not initialized with any arguments. In fact, empty parentheses cannot be used to call the default constructor.
// http://www.cplusplus.com/doc/tutorial/classes/ // overloading class constructors #include <iostream> using namespace std; class Rectangle { int width, height; public: Rectangle (); Rectangle (int,int); int area (void) {return (width*height);} }; Rectangle::Rectangle () { width = 5; height = 5; } Rectangle::Rectangle (int a, int b) { width = a; height = b; } int main () { Rectangle rect (3,4); Rectangle rectb; // ok, default constructor called Rectangle rectc(); // function declaration, default constructor NOT called cout << "rect area: " << rect.area() << endl; cout << "rectb area: " << rectb.area() << endl; cout << "rectc area: " << rectc.area() << endl; // error return 0; }
When we compile it, we will get an error
In function 'int main()': 29:35: error: request for member 'area' in 'rectc', which is of non-class type 'Rectangle()'
Defining class member functions and member initializer list
Use the single colon and a parenthesis. The parenthesis method can be used in the general variables intialization.
This method is particular necessary when we want to initialize a constant member value. See how to initialize const member variable in a class C++ in stackoverflow.com. The constant assignment happens in initializer list, much before the class initilization occurs.
See Single colon or 9.4.4 of Programming: principles and practice, 9.5.1 of Accelerated C++.
class Date { public: Date(int yy, int mm, int dd) :y(yy), m(mm), d(dd) { ... } void add_day(int n) { ... } int month() { return m; } ... private: int y, m, d; // year, month, day };
The :y(yy), m(mm), d(dd) notation is how we initialize members. It is called a member initializer list (See also this article in cplusplus.com). We could also use assignment to do the same job (not as good as the above way)
Date(int yy, int mm, int dd) { y = yy; m = mm; d = dd; // ... }
If we want to initialize private variables with value 0, we can do it too now.
class Student_info { public: Student_info(); Student_info(std::istream&); private: std::string n; double midterm, final; std::vector<double> homework; }; Student_info::Student_info() : midterm(0), final(0) { }
explicit keyword and implicit conversion to resolve the parameters to a function
http://stackoverflow.com/questions/121162/what-does-the-explicit-keyword-in-c-mean
Class constructor can take parameter via assignment
For example (see p6 & p76 of the [MIT lecture note)
class Integer { public: int val; Integer(int v) { val = v; cout << "constructor with arg " << v << endl; } }; int main() { Integer i(3); Integer j = 5; }
The output will be
constructor with arg 3 constructor with arg 5
copy constructor and copy assignment (operator=)
- See Chapter 11.3 of Accelerate C++
- Cplusplus.com
- See Chapter 18.3.1 and 18.3.2 of Programming: Principles and Practice (2nd ed).
copy constructor
MyClass(const MyClass& arg); </pre> To use it, <pre> MyClass v1(3); MyClass v2 = v1; // OR MyClass v2 {v1};
copy assignment
MyClass& MyClass::operator=(const MyClass& a) </pre> To use it, <pre> MyClass v1(3); v1.set(2, 2.2); MyClass v2(4); v2 = v1;
Operator Overloading
- http://www.learncpp.com/cpp-tutorial/91-introduction-to-operator-overloading/
- Chapter 11 Working with Classes -> Operator Overloading of C++ Primer Plus
- Chapter 11 Working with Classes -> Overloaded Operators: Member vs Nonmember Functions of C++ Primer Plus.
An operator function has the form
operatorOP(argument-list)
For many operators, you have a choice between using member functions or nonmember functions to implement operator overloading. Typically, the nonmember version is a friend function so it can directly access the private data for a class.
Case 1 (member function): Suppose both object1 and object2 belong to some class T, then the operation
object1 + object2
is the same as
object1.operator+(object2)
if we have implemented an appropriate operator+(const T &t) function in class T.
Case 2 (nonmember function):
friend T operator+(const T & t1, const T & t2);
Case 3 (nonmember function): Another example is object1 and object2 belong to different classes.
cout << object
comes from a nonmember friend function
void operator<<(ostream & os, const Time &t) { ... } // OR better with (see p519-520) friend std::ostream & operator<<(std::ostream &os, const Time &t) { ... }
Case 4 (nonmember function): In another situation (see C++ Primer Plus -> Chapter 11 -> Creating Friends), the statement
ConstantVariable + object // OR operator+(ConstantVariable, object)
where operator+() is a nonmember friend function; e.g.
friend T operator+(double m, const T &t) { ... }
An example
From Chapter 11 of the C++ Primer Plus.
Class | Main | |
---|---|---|
Ex1 | class Time { public: Time Sum(const Time &t) const; } |
Time time1, tim2, total; total = time1.Sum(time2); |
Ex2 | class Time { public: Time operator+(const Time &t) const; } |
total = time1.operator+(time2); // OR total = time1 + time2; |
Friend functions & classes
- http://www.cplusplus.com/doc/tutorial/inheritance/ (w/ a complete example, the friend function does not below any any class)
http://www.cprogramming.com/tutorial/friends.html(the friend function belongs to anothe class but why does it not include an argument??, confusing)- http://www.learncpp.com/cpp-tutorial/813-friend-functions-and-classes/ (the examples are Ok)
- Chapter 19.4 Friends of The C++ Programming Language.
- Chapter 11 Working with Classes/Introducing Friends of C++ Primer Plus (it uses overloading the << and * operator as an example; see the code <mytime3.h>, <mytime3.cpp> and <usetime3.cpp> here)
- Chapter 15 Friend classes in C++ Primer Plus. Friend classes are probably more practical than friend functions.
Idea of friend functions
We want some general function (see examples below) or a member function of some class (see http://www.cprogramming.com/tutorial/friends.html) to access the (private, protected and public) members of one or more classes.
By declaring a nonmember function a friend, we can give it to access the private part of the class declaration. A friend declaration can be placed in either the private or the public part of a class declaration; it does not matter where. (Chapter 19.4 Friends of The C++ Programming Language)
Note that when friends are specified within a class, this does not give the class itself access to the friend function. That function is not within the scope of the class; it's only an indication that the class will grant access to the function (http://www.cprogramming.com/tutorial/friends.html).
For example, we could define an operator that multiplies a Matrix and a Vector. The implementation routine cannot be a member of both. Also, we don't want to provide low-level access function to allow every user to both read and write the complete representation of both Matrix and Vector. To avoid this, we declare the operator* a friend of both.
constexpr int rc_max {4]; // row and column size class Matrix; class Vector { float c[rc_max]; // ... friend Vector operator*(const Matrix&, const Vector&); // operator*() can reach into the implementation of Vector. }; class Matrix { Vector v[rc_max]; // ... friend Vector operator*(const Matrix&, const Vector&); // operator*() can reach into the implementation of Matrix. }; Vector operator*(const Matrix& m, const Vector& v) { Vector r; ... return r; }
Now operator*() can reach into the implementation of both Vector and Matrix.
Other examples: std::ostream& operator<< operator as in freebayes and Rserve.
More examples from operator functions
Consider the following (C++ Primer Plus)
time2 = time1 * 2.75; // is the same as time2 = time1.operator*(2.75);
But the following statement is unclear because 2.75 is not a type Time object.
time2 = 2.75 * time1;
One solution is to use a nonmember function. So the compiler could match the expression time2 = 2.75 * time1 to the following nonmember function call: time2 = operator*(2.75, time2). However, nonmember functions can't directly access private data in a class. This is how friends comes.
See <mytime3.h> (the friend keyword in front of line 20 is required). It is a little tricky to understand the lines 20&21 at first. The function is a nonmember function (written in an inline way) and thus the keyword friend is necessary.
Overloading the << Operator
A common use of friend is overloading the << operator.
// mytime3.h class Time { public: friend std::ostream & operator<<(std::ostream &os, const Time &t); }; // mytime3.cpp std::ostream & operator<<(std::ostream& os, const Time &t) { os << t.hours << " hours, " << t.minutes << " minutes"; } // usetime3.cpp int main() { Time aida, tosca; cout << aida << "; " << tosca << endl; }
Inheritance
protected keyword in the base class
See an example from Accelerated C++ Chapter 13.1.
Suppose there is a base class and a derived class. Then the private functions and members in the base class cannot be accessed from outside of the base class. But if we declare these functions and members as protected, then we give derived classes access to the protected members of their constituent base-class objects, but keeps these elements inaccessible to users of the classes.
That is, members declared in protected are designed for the derived class. This should not be confused with the friend keyword.
See the example in cplusplus.com.
Polymorphism
http://www.cplusplus.com/doc/tutorial/polymorphism/
A function's signature is its argument list. You can define two functions having the same name, provided that they have different signatures. This is called function polymorphism.
Function polymorphism is also called function overloading.
Virtual functions
http://www.cplusplus.com/doc/tutorial/polymorphism/
Class 1 ^ | | v Class 2 (child)
(See 13.2.1 in Accelerated C++) Suppose we have two classes: one is a base class and the other is a derived class. Both of them have defined their own function called grade(). Then if we have defined a function as
bool compare_grades(const Base& c1, const Base& c2) { return c1.grade() < c2.grade(); }
then there is no way to distinguish between these two versions of grade() function. When we execute the compare_grades() function, it will always execute the Base::grade() member.
If we want C++ to use Derived::grade() member in compare_grades(), we can use C++ virtual functions:
class Base { public: virtual double grade() const; ... }
Now when we call compare_grades(), the implementation will determine the version of grade() to execute by looking at the actual types of the objects to which the reference c1 and c2 are bound. That is, if the argument is a Derived object, it will run Derived::grade() function; if the argument is a Base object it will run the Base::grade() function.
The virtual keyword may be used only inside the class definition. If the functions are defined separately from their declaration, we do not repeat virtual in the definitions.
(See OOP Demystified Chapter 4.3: Run-time polymorphism) Virtual functions may be actual functions or merely placeholders for real functions that derived classes must provide. If you define a virtual function without a body, that means the derived class must provide it (it has no choice, and the program will not compile otherwise). Classes with such functions are called abstract classes, because they aren’t complete classes and are more a guideline for creating actual classes. (For example, an abstract class might state “you must create the Display() method.”) In C++, you can create a virtual function without a body by appending =0 after its signature (also known as a pure virtual function).
(Rserve R package). The cxx client header file <Rconnection.h>
class Rexp { public: virtual Rsize_t length() { return len; } virtual std::ostream& os_print(std::ostream& os) { return os << "Rexp[type=" << type << ",len=" << len <<"]"; } }; class Rinteger : public Rexp { public: virtual Rsize_t length() { return len/4; } virtual std::ostream& os_print (std::ostream& os) { return os << "Rinteger[" << (len/4) <<"]"; } }; class Rdouble : public Rexp { public: virtual Rsize_t length() { return len/8; } virtual std::ostream& os_print (std::ostream& os) { return os << "Rdouble[" << (len/8) <<"]"; } };
Template
C++ uses templates to enable generic programming techniques. The C++ Standard Library includes the Standard Template Library (STL) that provides a framework of templates for common data structures and algorithms.
There are two kinds of templates: function templates (e.g. algorithm library) and class templates (e.g. array, vector, list containers).
Generic Programming & STL
- Generic programming is an approach to programming that focuses on algorithm reuse (to contrast, OOP focuses on data reuse). Read What is generic Programming ?. For example, a find function would work with arrays (int, double,...) or linked lists or any other container type. That is, not only should the function be independent of the data type stored in the container, it should be independent of the data structure of the container itself.
- A goal of generic programming is to write code that is independent of data types and data structures/containers. Templates are the C++ tools for creating generic programs. The STL goes further by providing a generic representation of algorithms. Chapter 16 of C++ Primer Plus.
Iterators (an extension of pointers)
Accelerated C++: Chapter 5. Using sequential containers and analyzing strings -> Iterators
// use indices for (vector<Student_info>::size_type i=0; i != students.size(); ++i) } cout << students[i].name << endl; } // use iterators for (vector<Student_info>::const_iterator iter = students.begin(); iter != students.end(); ++iter) { cout << (*iter).name << endl; // OR // cout << iter->name << endl; }
Note that
- const_iterator means the iterator is used for access only, and cannot be used for modification.
- students.begin() and students.end() return an iterator.
- Iterators can be used in a while() loop in addition to a for() loop; see <fails_iters.cc>.
- We can use iter (not *iter) to specify the element that is to be erased; see common operations and an example.
C++ Primer Plus Chapter 16. The string class and the STL -> Generic programming -> Why iterators
Understanding iterators is the key to understanding the STL.
Just as template make algorithms independent of the type of data stored, iterators make the algorithms independent of the type of container (array, list, set, map, ...) used.
For example consider the find function which would work on different container types. We need a generic representation of the process of moving through the values in a container. The iterator is that generalized representation.
An iterator should contain some properties. See also Iterators.
- Able to dereference an iterator in order to access the value. If p is an interator, *p should be defined.
- Able to assign one iterator to another. The expression p = q should be defined.
- Able to compare two iterator for equality. The expression p == q and p != q should be defined.
- Able to move an iterator through all the element of a container. ++p and p++ Should be defined.
The following example shows how the pointers can be extended to iterators.
// Method 1. pointers // If the function finds the value in the array, it returns the address in the array // where the value is found; otherise, it returns the null pointer. double * find_ar(double * ar, int n, const double * val) { for (int i = 0; i < n; i++) if (ar[i] == val) return &ar[i]; return 0; } // Method 2. Self-defined iterator type typedef double * iterator; iterator find_ar(iterator ar, int n, const double & val) { for (int i = 0; i < n; i++, ar++) if (*ar == val) return ar; return 0; } // Method 3. More like a STL function style // The function can return the end of pointer as a sign the value was not found. // http://www.cplusplus.com/reference/algorithm/find/?kw=find typedef double * iterator; iterator find_ar(iterator begin, iterator end, const double & val) { iterator ar; for (ar = begin; ar != end; ar++) if (*ar == val) return ar; return end; // indicates val not found }
Function templates
http://www.cplusplus.com/doc/tutorial/templates/
// function template #include <iostream> using namespace std; template <class T> T GetMax (T a, T b) { T result; result = (a>b)? a : b; return (result); } int main () { int i=5, j=6, k; long l=10, m=5, n; k=GetMax<int>(i,j); n=GetMax<long>(l,m); cout << k << endl; cout << n << endl; return 0; }
Another example is exchanging two variables. See Listing 8.11 <funtemp.cpp> in C++ Primer Plus (5th ed).
template <class Any> void Swap(Any &a, Any &b) { // References as Function Arguments Any temp; temp = a; a = b; b = temp; } int main() { int i = 10, j= 20; Swap(i, j); cout << "New i, j = " << i << ", " << j << ".\n"; double x = 24.5, y = 81.7; Swap(x, y); cout << "New x, y = " << x << ", " << y << ".\n"; }
Or Overloaded Templates. See Listing 8.12 <twotemps.cpp> in C++ Primer Plus (5th ed).
template <class Any> void Swap(Any &a, Any &b) template <class Any> void Swap(Any *a, Any *b, int n); int main() { int i=10, j=20; Swap(i, j); int d1[8] = {0, 7, 0, 4, 1, 7, 7, 6}; int d2[8] = {0, 6, 2 ,0, 1, 9, 6, 9}; Swap(d1, d2, 8); } template <class Any> void Swap(Any &a, Any &b) { Any temp; temp=a; a=b; b=temp; } template <class Any> void Swap(Any a[], Any b[], int n) { Any temp; for (int i=0; i<n; i++) { temp = a[i]; a[i] = b[i]; b[i]=temp; } }
Class templates
http://www.cplusplus.com/doc/tutorial/templates/
// class templates #include <iostream> using namespace std; template <class T> class mypair { T a, b; public: mypair (T first, T second) {a=first; b=second;} T getmax (); }; template <class T> T mypair<T>::getmax () { T retval; retval = a>b? a : b; return retval; } int main () { mypair <int> myobject (100, 75); cout << myobject.getmax(); return 0; }
Alternative to int
std::size_t
http://en.cppreference.com/w/cpp/types/size_t and http://www.cplusplus.com/reference/cstring/size_t/
According to http://www.cplusplus.com/forum/beginner/15959/, size_type was most used inside the STD containers.
#include <iostream> #include <string> int main () { std::string str ("This is a book."); std::size_t i, j; std::cout << "The size of str is " << str.size() << " bytes.\n"; // 15 i=0; j=4; std::cout << str.substr(i, j) << std::endl; // "This" return 0; }
std::string::size_type
http://www.cplusplus.com/reference/string/string/
size_type is an unsigned type of container subscripts, element counts, etc. It is conceivable that an int is insufficient to contain the length.
const std::string::size_type cols = myString.size() + 2;
std::vector<TYPE>::size_type
http://www.cplusplus.com/reference/vector/vector/
In vector, size_type is used as an index in a for-loop. See an example at vector case.
String, iterator and printing
The iterator is one of string's member types and begin() & end() are two string's member functions with return type of iterators.
An iterator is a generalization of a pointer. You can print the value by using star (*) to deference, use +/- to move it and use != to compare different iterators. Moreover, we can use subset operator [] to get elements (eg iter[-1]).
Usually an iterator is used in sequences or vectors, see Sequence.
// string::begin/end #include <iostream> #include <string> int main () { std::string str ("Test string"); for ( std::string::iterator it=str.begin(); it!=str.end(); ++it) std::cout << *it; std::cout << '\n'; return 0; }
snprintf() and sprintf()
See http://www.cplusplus.com/reference/cstdio/sprintf/
- int snprintf(char *s, size_t n, const char * format, ...)
- int sprintf(char *s, const char * format, ...)
String, string, string
12 C++ String Methods You Should Master Today
http://stackoverflow.com/questions/11322200/unable-to-build-my-c-code-with-g-4-6-3
http://stackoverflow.com/questions/2258561/getting-the-length-of-an-array-using-strlen-in-g-compiler
Learn C Essentials by MagPi
- C++ uses <cstring> for char*, strlen, strcpy ...
- C uses <string.h> for char*
- C++ uses <string> for string class & <sstream> for stringstream class.
- Qt uses QString & QStringList from <QtCore>, QTextStream from <QTextStream>. Cf QDataStream from <QDataStream>.
Convert a c-style string to a c++ string
char * mystr = "klajlfdjlajfd"; std::string mycppstr(mystr);
string::size_type
padding
- Use std::setw() http://stackoverflow.com/questions/667183/padding-stl-strings-in-c
- Use "+" operation
Example:
#include <iostream> #include <string> #include <iomanip> // std::setw using namespace std; int main() { string str; str = "abcd"; cout << setw (10) << str << endl; cout << str + string(4, ' ') + str << endl; return 0; } /* Output: abcd abcd efgh */
Comparison
P50 of Learn C Essentials - <string.h> library.
- C-string
char key[] = "apple"; char buffer[80]; do { printf ("Guess my favorite fruit? "); fflush (stdout); scanf ("%79s",buffer); } while (strcmp (key,buffer) != 0);
- C++ string
std::string str1 ("green apple"); std::string str2 ("red apple"); if (str1.compare(str2) != 0) std::cout << str1 << " is not " << str2 << '\n';
Remove file name & Get the basename from a full path: substr(), find_last_of()
- These two actions correspond to the dirname and basename commands in Linux OS.
- Use string::find_last_of() and string::substr() functions. See http://stackoverflow.com/questions/10364877/c-how-to-remove-filename-from-path-string
#include <iostream> using namespace std; int main() { // This solution works with both forward and back slashes. string s1("../somepath/somemorepath/somefile.ext"); string s2("..\\somepath\\somemorepath\\somefile.ext"); // Remove file name from a full path cout << s1.substr(0, s1.find_last_of("\\/")) << endl; // s1 is not changed yet cout << s2.substr(0, s2.find_last_of("\\/")) << endl; // use s1=s1.substr() to change it // Get the basename cout << s1.substr(s1.find_last_of("\\/")+1) << endl; cout << s2.substr(s2.find_last_of("\\/")+1) << endl; return 0; }
The output is
../somepath/somemorepath ..\somepath\somemorepath somefile.ext somefile.ext
Extract the file name and extension from a string: find_last_of()
Replace a substring
- Use the string::find() or (this) and string::replace() functions. See http://stackoverflow.com/questions/3418231/replace-part-of-a-string-with-another-string
#include <iostream> using namespace std; bool replace(std::string& str, const std::string& from, const std::string& to) { size_t start_pos = str.find(from); if(start_pos == std::string::npos) return false; str.replace(start_pos, from.length(), to); return true; } int main() { std::string string("/home/brb/igenomes/Homo_sapiens/Ensembl/GRCh37/Sequence/BWAIndex/"); replace(string, "GRCh37", "GRCh38"); cout << string << endl; return 0; }
The output is
/home/brb/igenomes/Homo_sapiens/Ensembl/GRCh38/Sequence/BWAIndex/
convert backslash to forward slash in string
In C++ (not tested)
string path = "C:\Program Files"; std::replace(path.begin(), path.end(), '\\', '/');
In Qt (tested), we can use
QString sReturnedValue = "C:\Program Files"; sReturnedValue.replace("\\", "/");
size method
- string object: Returns the length of the string, in terms of bytes.
- vector object: Return the number of elements.
Convert
Danger of implicit type conversion
Implicit type conversion (coercion) can result in unexpected results. See the following example.
#include <iostream> #include <iomanip> using namespace std; int main() { float myFloat; long int myInt = 123456789; // long int are 32-bit signed integers with a range -2147483648 to 2147483647. myFloat = myInt; streamsize prec=cout.precision(); cout << "myInt is changed to" << setprecision(9) << myFloat << setprecision(prec) << endl; // 123456792. It is not a typo! return 0; }
Implicit types conversion rules:
- long int to float can cause wrong results
- float to int removes the decimal part
- double to float rounds digit of double
- long int to int drops the encoded higher bits
Convert char* to string
std::string has a constructor that takes a char*.
char *path = "Eggs on toast."; std::string str = std::string(path);
Convert std::string to c-string/char *
See
- stackoverflow A
- stackoverflow B
- www.cplusplus.com
- codeguru.com.
- http://stackoverflow.com/questions/12862739/convert-string-to-char
char * S = new char[R.length() + 1]; std::strcpy(S,R.c_str());
This is useful when we want to use the ifstream class to open a file where the file name is a string. The standard streams doesn't accept a standard string, only c-string! So pass the string using c_str():
Table::Table(string filename) { ifstream fin; fin.open(filename.c_str()); ... }
Convert an integer to character string
See www.cplusplus.com.
We need to include
#include <sstream>
Convert a numerical number to char
Use
char mychar[256]=""; double number; sprintf_s(mychar, "%0.2f", number);
This will save a number for example -7.035425 to -7.03 as characters.
C++ IO Streams
- http://www.cprogramming.com/tutorial/c++-iostreams.html
- http://www.cplusplus.com/doc/tutorial/files/
- The filename used in the open() method requires a C-style string argument:
- argv[i] from main()
- explicit string like "myfile"
- convert from a string object by using the c_str() method like filename.c_str()
The first example is to read the input filename using command line argument (Accelerated C++ Chapter 10.5).
#include <iostream> #include <fstream> int main(int argc, char **argv) { int fail_count = 0; // for each file in the input list for (int i = 1; i < argc; ++i) { ifstream in(argv[i]); // if it exists, write its contents, otherwise generate an error message // another way is to use (in.is_open() == false) to check if the file can be opened; see other places if (in) { string s; while (getline(in, s)) cout << s << endl; } else { cerr << "cannot open file " << argv[i] << endl; ++fail_count; } } return fail_count; }
The 2nd example is to hard-code the input filename.
#include <fstream> #include <string> using std::endl; using std::getline; using std::ifstream; using std::ofstream; using std::string; int main() { ifstream infile("in"); ofstream outfile("out"); string s; while (getline(infile, s)) outfile << s << endl; infile.close(); outfile.close(); return 0; }
No matching function - ifstream open()
If we want to use a string type as a file name instead of specifying the file name in the code (hard-code), we need to use the c_str member function first.
See here. It Change to:
std::string filename std::ifstream infile; infile.open(filename.c_str()); # Or std::ifstream infile(filename.c_str());
An argument natural to ifstream is argv[i] from main(). For example,
ifstream in(arv[i]);
If we want to check if the open operation is successful or not, we can not use statement like
if (file.open()) { ... }
We need to use ether if (infile) or infile.is_open() function or declare filename as filebuf* type and the open() function will return NULL if the file cannot be opened. See an example in cplusplus.com.
Support for std::string argument was added in c++11.
fail(), bad() and eof() functions
- fail() means logical error. An example of its usage after .open()
- bad() means read/write error. Possible causes are more complex like memory shortage or buffer throws an exception. See an answer from stackoverflow.com.
Here is an example from cppreference.com to test bad(), eof() and fail() methods.
stringstream
- http://www.cplusplus.com/reference/sstream/stringstream/
- http://en.cppreference.com/w/cpp/io/basic_stringstream
Since stringstream is based on sstream, a stringstream is closer to stream (or file) rather than a string.
Simple example (using multiple << and >> operators)
// swapping ostringstream objects #include <string> // std::string #include <iostream> // std::cout #include <sstream> // std::stringstream int main () { std::stringstream ss; ss << 100 << ' ' << 200; int foo,bar; ss >> foo >> bar; std::cout << "foo: " << foo << '\n'; std::cout << "bar: " << bar << '\n'; return 0; } // Output: // foo: 100 // bar: 200
stringstream::str
#include <string> // std::string #include <iostream> // std::cout #include <sstream> // std::stringstream, std::stringbuf int main () { std::stringstream ss; ss.str ("Example string"); std::string s = ss.str(); std::cout << s << '\n'; return 0; } // Output: // Example string
Clean/empty a stringstream
See stringstream.
std::stringstream ss; ss.str("");
P.S. The clear() member function is inherited from ios and is used to clear the error state of the stream only. For some reason, it is necessary to use the clear() function inside a loop call. Another method is to declare a stringstream variable inside a loop.
clear() and rdstate() functions
stringstream is related to reading. We call clear() to reset the error state, which tells the library that input can continue despite the failure. Note that clear() is also used in vector objects.
#include <iostream> // std::cout #include <fstream> // std::fstream int main () { char buffer [80]; std::fstream myfile; myfile.open ("test.txt",std::fstream::in); myfile << "test"; if (myfile.fail()) { std::cout << "Error writing to test.txt\n"; myfile.clear(); } myfile.getline (buffer,80); std::cout << buffer << " successfully read from file.\n"; return 0; }
And convert a string from in input to integers.
- http://www.cplusplus.com/forum/beginner/47814/
- http://stackoverflow.com/questions/541022/stringstream-extract-integer
#include <sstream> #include <vector> #include <iostream> using namespace std; int main() { string Digits("11 22 33"); stringstream ss(Digits); string Temp; vector<string>Tokens; while(ss >> Temp) Tokens.push_back(Temp); if (ss.rdstate() != 0) { cout << "not goodbit" << endl; } else cout << "goodbit" << endl; // When the stream extracts the last of the 3 digist "1 2 3", the eof state will be set. // You have to reset all status flags (eofbit) and bring the stream into a good state (goodbit): // After that, read operations will be canceled and you have to clear that flag out again. // Anyway, after clearing and resetting the string, you can then go on extracting the integers. ss.clear(); // clear the flag; it is not needed for the next line (ss.str(Tokens[0]), // but for the line of ss >> Num; // Without this line, building the program is OK but the output of Num is 0. if (ss.rdstate() != 0) { cout << "not goodbit" << endl; } else cout << "goodbit" << endl; ss.str(Tokens[0]); cout << ss.str() << endl; int Num = 0; ss >> Num; cout << Num << endl; } // Output: // 11
And an example to verify if the string is an integer (by converting a string to a stringstream, and then use the ">>" extract operator)
#include <sstream> #include <iostream> using namespace std; int main() { std::stringstream ss; std::string input = "a b c 4 e"; ss << input; if (ss.rdstate() != 0) { cout << "not goodbit" << endl; } else cout << "goodbit" << endl; int found; std::string temp; while(std::getline(ss, temp,' ')) { if(std::stringstream(temp)>>found) { std::cout<<found<<std::endl; } } if (ss.rdstate() != 0) { cout << "not goodbit" << endl; } else cout << "goodbit" << endl; return 0; } // Output: // goodbit // 4 // not goodbit
getline() function to extract
istream/ostream, iostream and fstream headers and files
How to read and write files in C++ I/O stream classes
See 4.1.2 the standard-library headers and namespace in The C++ Programming Language. The standard library is defined in a namespace called std.
- iostream include cin, cout, cerr, clog, istream and ostream
- fstream includes ifstream and ofstream. These two are useful for files i/o. Note ostream is termed a base class and ofstream class is based on it. ofstream is termed a derived class.
(10.5.2 in Accelerated C++) It is possible to use an ifstream wherever the library expects an istream and an ofstream wherever the library expects an ostream???
Read from console: std::cin >>
We need to include the header file <iostream>.
Note that this is different from std::istream read() which requires the header file <fstream> and it is used for accessing files.
What is std::cin and if (cin >> x)
https://stackoverflow.com/questions/6791520/if-cin-x-why-can-you-use-that-condition
int x; if (cin >> x){}
is equivalent to
cin >> x; if (cin){}
Create a vector: input from cin
#include <iostream> #include <vector> using namespace std; int main() { vector<double> temps; // temperatures double temp; while (cin >> temp) // read temps.push_back(temp); // put into vector cout << "length of the vector is " << temps.size() << endl; for (const auto tmp : temps) cout << tmp << " "; cout << "\n"; }
Hit the 'Enter' key first and then use 'ctrl+d' to end the input.
$ g++ -std=c++11 foo.cpp $ cat > input.txt 4 3 2 1 9.0 $ ./a.out < input.txt length of the vector is 5 4 3 2 1 9
Another example is <main1.cc> from Accelerated C++ Chapter 4. The function read_hw() uses std::istream as the type instead of std::cin to read from the console. It also has a return type std::istream.
#include <iostream> // std::cin, std::istream using std::cin; using std::istream; istream& read_hw(istream& in, vector<double>& hw) { ... } int main() { ... vector<double> homework; read_hw(cin, homework); ... }
Create a map (key-index vector) object (word count)
This is example code from Chapter 21.6.1 "Map" of PPP.
#include <iostream> #include <map> #include <string> using namespace std; //------------------------------------------------------------------------------ int main() { map<string,int> words; // keep (word,frequency) pairs string s; while (cin>>s) ++words[s]; // reads every whitespace-separated word on input // note: words is subscripted by a string typedef map<string,int>::const_iterator Iter; for (Iter p = words.begin(); p!=words.end(); ++p) cout << p->first << ": " << p->second << '\n'; }
$ ./chapter.21.6.1.exe b b c c a ab ab a: 1 ab: 2 b: 2 c: 2
It seems the words are sorted too.
Directory
Check if a directory exists or not
http://stackoverflow.com/questions/3828192/checking-if-a-directory-exists-in-unix-system-call
#include <sys/stat.h> struct stat sb; if (stat(pathname, &sb) == 0 && S_ISDIR(sb.st_mode)) { ...it is a directory... }
Create a directory in Linux
http://codeyarns.com/2014/08/07/how-to-create-directory-using-c-on-linux/
#include <sys/stat.h> const int dir_err = mkdir("foo", S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH); if (-1 == dir_err) { printf("Error creating directory!n"); exit(1); }
Note that this does not create parent directories .
List files in a directory
http://www.linuxquestions.org/questions/programming-9/c-list-files-in-directory-379323/
File
Delete a file
Use C library stdio; i.e. include <stdio.h> or <cstdio>. See also remove. Note that according to The Linux Programming Interface book, remove() function removes a file or an empty directory. The empty directory part was not mentioned on website??
#include <iostream> #include <stdio.h> int main() { remove("myfile.txt"); return 0; }
A convenient way to see the manual is to use man remove.
On LInux,
REMOVE(3) Linux Programmer's Manual REMOVE(3) NAME remove - remove a file or directory SYNOPSIS #include <stdio.h> int remove(const char *pathname);
On Mac,
REMOVE(3) BSD Library Functions Manual REMOVE(3) NAME remove -- remove directory entry SYNOPSIS #include <stdio.h> int remove(const char *path);
Reading a table file
Line ending difference between DOS and UNIX text file
The DOS text file has two ending characters (CR + LF) while UNIX text file has only 1 ending character (LF). This may create two answers when we want to count the number of columns in a row or compare the elements from the last column.
For example, if a text file is created from DOS, it will look like below on Linux OS.
"ID 1 2 3 4 5 6 7 8 9 10 "
In this case, the last element is read in as 10[CR] instead of 10 on Linux. So if you need to run string/character comparison, you may not able to get what you want.
But if we remove the trailing \r character ( tr -d '\r' < INPUT > OUTPUT), we will obtain
"ID 1 2 3 4 5 6 7 8 9 10"
Interestingly, if we use winscp to transfer text files from Linux to Windows, it automatically add \r character to text files.
- If we want to convert files using dos2unix/unix2dos, we just need to specify the input file. By default, the input file will be overwritten.
dos2unix inputoutputfile unix2dos inputoutputfile
- Normally when we create a file, the file has a LF character (or CR + LF). So when we using 'cat command, the output is normal.
brb@brb-T3500:~/Downloads$ cat combobox.txt ID 1 2 3 1 -0.80 -0.30 -0.41 brb@brb-T3500:~/Downloads$
But if we remove the last line's LF character (eg using Window's notepad or geany editor)
brb@brb-T3500:~/Downloads$ cat combobox.txt ID 1 2 3 1 -0.80 -0.30 -0.41brb@brb-T3500:~/Downloads$
Count number of lines in a text file --- std::ifstream & getline()
We need to include the header <fstream>.
http://stackoverflow.com/questions/3482064/counting-the-number-of-lines-in-a-text-file
Method 1. Succinct
#include <iostream> // std::cout #include <fstream> // std::ifstream #include <string> // std::getline using namespace std; int main() { int number_of_lines = 0; std::string line; ifstream fin; fin.open("combobox.txt"); // assume the file uses tab as delimiter while (std::getline(fin, line)) ++number_of_lines; std::cout << "Number of lines in text file: " << number_of_lines; return 0; }
Very reliable. Don't need to worry about an empty line at the end of the file.
Method 2. Good, but lenghy
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { int number_of_lines = 0; std::string line; ifstream fin; fin.open("combobox.txt"); // assume the file uses tab as delimiter std::getline(fin, line); while (fin) { ++number_of_lines; std::getline(fin, line); } std::cout << "Number of lines in text file: " << number_of_lines; return 0; }
Method 3. Not good. Need extra correction
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { int number_of_lines = 0; std::string line; ifstream fin; fin.open("combobox.txt"); // assume the file uses tab as delimiter while (fin.good()) { ++number_of_lines; std::getline(fin, line); } --number_of_lines; // need an extra step std::cout << "Number of lines in text file: " << number_of_lines; return 0; }
Read a text file and one character at a time (using get())
void foo(ifstream& fin, ofstrea& fout) { char next; fin.get(next); while (! fin.eof()) { if (next == 'A') fout << "A++"; else fout << next; fin.get(next); } }
Read a text file with one row only (using getline())
#include <iostream> #include <fstream> #include <string> using namespace std; int main() { ifstream fin; fin.open("combobox.txt"); // assume the file uses tab as delimiter if (fin.is_open() == false) { cout << "Can't open file combobox.txt. Bye." << endl; return 1; } string item; int count = 0; getline(fin, item, '\t'); while (fin) { ++count; cout << count << ": " << item << endl; getline(fin, item, '\t'); } cout << "Done\n"; fin.close(); }
If the input file 'combobox.txt' looks like (the [LF] is line feedback, hidden character),
ID 1 2 3[LF] 1 -0.80 -0.30 -0.41[LF]
the output will look like
1: ID 2: 1 3: 2 4: 3 1 5: -0.80 6: -0.30 7: -0.41 Done
Explanation
- After the element 2, the next element is 3[LF]1. So the output looks a little strange.
- After the element -0.30, the next element is -0.41[LF]. The there is an extra blank line there.
- The output is the same if the end of line is in DOS format (CR + LF).
Read a text file with multiple columns --- std::stringstream and getline()
With the following examples, we can count the number of columns and number of rows of a text file.
Solution 1.
#include <iostream> #include <fstream> #include <string> #include <sstream> // stringstream #include <stdlib.h> /* exit, EXIT_FAILURE */ using namespace std; int main() { ifstream fin; fin.open("combobox.txt"); // step 1. open a file if (fin.is_open() == false) { cout << "Can't open file. Bye." << endl; exit(EXIT_FAILURE); } string line, item; int ncol = 0, nrow = 0; stringstream iss; while(getline(fin, line)) { // step 2. extract a line ("\n" is the default delimiter) from a (file) stream nrow++; // accumulate row number. iss << line; // step 3. insert a string to a stringstream // Assume data is tab delimited // http://www.cplusplus.com/reference/string/string/getline/ while (getline(iss, item, '\t')) { // step 4. extract a string from a stringstream if (nrow == 1 ) ++ncol; // accumulate column number. cout << item << endl; } // For numerical data, we can use // double value; // while (iss >> value) { } iss.clear(); // step 5. clear the error state of the stream? } cout << "There are " << nrow << " rows and " << ncol << " columns\n"; fin.close(); }
If we want to assign the column names to an array of string and elements to 2 2D string arrays, we need to determine the dimension and then declare the variables first.
col_names = new string[ncol]; for(int i=0;i<ncol;i++){ getline(iss, col_names[i], '\t'); } fin.clear(); fin.seekg(0, ios::beg); element = new string *[nrow]; stringstream iss; string str; for(int i=0;i<nrow;i++){ getline(fin, line); iss << line; element[i] = new string[ncol]; for(int j=0;j< ncol;j++){ if(getline(iss, str, '\t') ) { element[i][j]=str; }else{ element[i][j]=string(""); } } iss.clear() }
Solution 2
- http://stackoverflow.com/questions/1075712/reading-delimited-files-in-c
- http://www.cplusplus.com/forum/general/17771/
typedef vector<vector<string> > Rows; Rows rows; ifstream input("filename.csv"); char const row_delim = '\n'; char const field_delim = '\t'; for (string row; getline(input, row, row_delim); ) { rows.push_back(Rows::value_type()); istringstream ss(row); for (string field; getline(ss, field, field_delim); ) { rows.back().push_back(field); } }
reset position to the beginning of file
ifstream orderfile; orderfile.open (fullpath); std::string line; long total_count=0; while (orderfile.good()){ getline(orderfile, line); if (!line.empty()) total_count++; } orderfile.clear(); orderfile.seekg(0,ios::beg); getline(orderfile, line);
Write a Function to Contain an Argument of Output Device (eg file, screen)
See Listing 8.8 <filefunc.cpp> in C++ Primer Plus (5th ed). It uses ostream & as the class of output device type in the function definition. For the main function, we can use objects of class ofstream or istream. Recall, ostream is a base class and ofstream is a derived class.
The program teaches
- use reference (ostream &) as a function argument to refer to an ostream object such as cout (#include <iostream>) and to an ofstream (#include <fstream>) object.
- how ostream formatting methods such as precisions(), setf() and width() can be used for both types.
int main() { ofstream fout; ... file_it(fout, objective, eps, LIMIT); ... } void file_it(ostream & os, double fo, const double fe[],int n) {}
Another example <analysis.gcc> can be found on Chapter 6 of Accelerated C++.
using std::cout; int main() { ... write_analysis(cout, "median", median_analysis, did, didnt); ... } void write_analysis(ostream& out, const string& name, double analysis(const vector<Student_info>&), const vector<Student_info>& did, const vector<Student_info>& didnt) {}
Sorting only
- C++ string sorting Note: qsort() in C won't work for string type in C++.
#include <iostream> #include <string> #include <iterator> #include <algorithm> int main() { std::string obj[4] = {"fine", "ppoq", "tri", "get"}; std::sort(obj, obj + 4); std::copy(obj, obj + 4, std::ostream_iterator<std::string>(std::cout, "\n")); // And for vector // #include <vector> // std::vector<std::string> stringarray; // std::sort(stringarray.begin(), stringarray.end()); }
and
#include <stdlib.h> #include <string.h> int compare_cstr(const void* c1, const void* c2) { return strcmp(*(const char**)(c1), *(const char**)(c2)); } int main() { const char* obj[4] = {"fine", "ppoq", "tri", "get"}; qsort(obj, 4, sizeof(obj[0]), compare_cstr); std::copy(obj, obj + 4, std::ostream_iterator<const char*>(std::cout, "\n")); }
Note: The use of ostream_iterator<string>(cout, "\n") was explained & used in Accelerated C++ Chapter 8.3 (Input and output iterators) & 8.4. It was also explained in cplusplus.com.
Return permutation (R's order() function) using 3 approaches
Good example. This is using lambda from C++0x but it can be replaced with simple functor object.
#include <vector> #include <algorithm> #include <iostream> template<class Vals> void sortingPermutation(const Vals& values, std::vector<int>& v){ int size = values.size(); v.clear(); v.reserve(size); for(int i=0; i < size; ++i) v.push_back(i); std::sort(v.begin(), v.end(), [&values](int a, int b) -> bool { return values[a] < values[b]; }); } int main() { std::vector<double> values; values.push_back(24); values.push_back(55); values.push_back(22); values.push_back(1); std::vector<int> permutation; sortingPermutation(values, permutation); typedef std::vector<int>::const_iterator I; for (I p = permutation.begin(); p != permutation.end(); ++p) std::cout << *p << " "; std::cout << "\n"; }
This will return values 3, 2, 0, 1. In fact, the code is so general: if I add #include <string> and change double to std::string in the declaration of values, the code works for string data type.
Method 2. You can use std::sort to sort the list of pairs {(24, 0), (55, 2), (22, 0), (1, 1)}.
#include <vector> #include <algorithm> #include <utility> typedef std::pair<double, int> Pair; struct CmpPair { bool operator()(const Pair& a, const Pair& b) { return a.first < b.first; } }; void sortingPermutation( const std::vector<double>& values, std::vector<int>& permutation) { std::vector<Pair> pairs; for (int i = 0; i < (int)values.size(); i++) pairs.push_back(Pair(values[i], i)); std::sort(pairs.begin(), pairs.end(), CmpPair()); typedef std::vector<Pair>::const_iterator I; for (I p = pairs.begin(); p != pairs.end(); ++p) permutation.push_back(p->second); } #include <iostream> int main() { std::vector<double> values; values.push_back(24); values.push_back(55); values.push_back(22); values.push_back(1); std::vector<int> permutation; sortingPermutation(values, permutation); typedef std::vector<int>::const_iterator I; for (I p = permutation.begin(); p != permutation.end(); ++p) std::cout << *p << " "; std::cout << "\n"; }
This will give the same result as above. In fact, the code is so general: if I add #include <string> and change double to std::string in the declaration of values, the code works for string data type. See also c version http://stackoverflow.com/questions/2804493/finding-unique-elements-in-an-string-array-in-c.
Method 3. Create a vector of ints 0..N and then sort that array with a comparison function that compares the corresponding elements of the vector you're trying to find the sorted permutation of. Something like:
#include <iostream> #include <algorithm> #include <vector> template<class T> class sorter { const std::vector<T> &values; public: sorter(const std::vector<T> &v) : values(v) {} bool operator()(int a, int b) { return values[a] < values[b]; } }; template<class T> std::vector<int> order(const std::vector<T> &values) { std::vector<int> rv(values.size()); int idx = 0; for (std::vector<int>::iterator i = rv.begin(); i != rv.end(); i++) *i = idx++; std::sort(rv.begin(), rv.end(), sorter<T>(values)); return rv; } int main() { std::vector<double> values; values.push_back(24); values.push_back(55); values.push_back(22); values.push_back(1); std::vector<int> permutation; permutation = order(values); typedef std::vector<int>::const_iterator I; for (I p = permutation.begin(); p != permutation.end(); ++p) std::cout << *p << " "; std::cout << "\n"; }
This also gives the same result. In fact, the code is so general: if I add #include <string> and change double to std::string in the declaration of values, the code works for string data type.
Infinity value
http://en.cppreference.com/w/cpp/types/numeric_limits/infinity
double max = std::numeric_limits<double>::max(); double inf = std::numeric_limits<double>::infinity(); if(inf > max) std::cout << inf << " is greater than " << max << '\n';
Scope
Method 1: Created object cannot be used in other places.
Class aClass { aClass(); void foo(); }; aClass::aClass() { bClass *obj = new bClass; } void aClass::foo() { obj->myfunction(); // Won't work!! }
Method 2: Created object can be used within the class.
Class aClass { aClass(); void foo(); }; aClass::aClass() { obj = new bClass; } void aClass::foo() { obj->myfunction(); }
C++11
- http://www.stroustrup.com/ and C++FAQ
- Ten C++11 Features Every C++ Developer Should Use
- http://en.wikipedia.org/wiki/C%2B%2B11
- http://www.stroustrup.com/C++11FAQ.html
- http://www.cprogramming.com/c++11/what-is-c++0x.html
To compile a code containing C++11 features (gcc 4.7 and up), using -std=c++11 or -std=c++0x option in g++
g++ -std=c++11 MYCODE.cc
regex
- http://www.cplusplus.com/reference/regex/
- http://en.cppreference.com/w/cpp/regex/
- http://www.johndcook.com/blog/cpp_regex/ (interesting but seems not working on my gcc 4.7)
- Need gcc 4.9 to support regex. See this post on stackoverflow.com.
regex_match() function
#include <algorithm> #include <iostream> #include <string> #include <regex> int main() { if (std::regex_match("yx12", std::regex("(.*x1.*)"))) std::cout << "string yx12 contains x1.\n"; if (std::regex_match("yx12", std::regex("(.*x2.*)"))) std::cout << "string yx12 contains x2.\n"; if (std::regex_match("yx12", std::regex("(.*yx1.*)"))) std::cout << "string yx12 contains yx1.\n"; }
See this post to match a string that does not contain some string.
Lambda functions
A lambda function is essentially an anonymous function (a function without a name) that’s defined inline.
- http://www.cprogramming.com/c++11/c++11-lambda-closures.html
- http://msdn.microsoft.com/en-us/library/dd293608(v=vs.100).aspx
- http://en.cppreference.com/w/cpp/language/lambda
- http://candrews.net/blog/2011/07/understanding-c-0x-lambda-functions/
- sorting and index
A simple example from an article from oracle.com.
#include <stdlib.h> #include <stdio.h> #include <algorithm> int main() { int a[10] = { 9, 8, 7, 6, 5, 4, 3, 2, 1, 0 }; std::sort( a, &a[10], [](int x, int y){ return x < y; } ); for(int i=0; i<10; i++) { printf("%i ", a[i]); } printf("\n"); return 0; }
STL vector vs C++ new
Basic STL vector
- http://www.cprogramming.com/tutorial/stl/vector.html
- http://www.cplusplus.com/reference/vector/vector/
Vectors examples:
#include <vector> using std::vector; vector<int> ivec; // ivec holds objects of type int vector<Sales_item> Sales_vec; // holds Sales_items vector<vector<string>> file; // vector whose elements are vectors # Initialize vectors vector<int> ivec; // initially empty vector<int> ivec2(ivec); // copy elements of ivec into ivec2 vector<int> ivec3 = ivec; // copy elements of ivec into ivec3 vector<string> svec(ivec2); // error: svec holds strings, not ints vector<string> articles = {"a", "an", "the"}; vector<int> ivec(10, -1); // ten int elements, each initialized to -1 vector<string> svec(10, "hi!"); // ten strings; each element is "hi!" vector<int> ivec(10); // ten elements, each initialized to 0 vector<string> svec(10); // ten elements, each an empty string vector<int> v1(10); // v1 has ten elements with value 0 vector<int> v2{10}; // v2 has one element with value 10 vector<int> v3(10, 1); // v3 has ten elements with value 1 vector<int> v4{10, 1}; // v4 has two elements with values 10 and 1 # Add an element to a vector vector<int> v2; // empty vector for (int i = 0; i != 100; ++i) v2.push_back(i); // append sequential integers to v2 // at end of loop v2 has 100 elements, values 0 . . . 99 # vector operators # v.empty() # v.size() # v.push_back(t) # v[n] # v1 = v2 # v1 = {a, b, c} # v1 == v2 # v1 != v2 # <, <=, >, >= vector<int> v{1,2,3,4,5,6,7,8,9}; for (auto &i : v) // for each element in v (note: i is a reference) i *= i; // square the element value for (auto i : v) // for each element in v cout << i << " "; // print the elemen vector<int> ivec; // empty vector for (decltype(ivec.size()) ix = 0; ix != 10; ++ix) ivec.push_back(ix); // ok: adds a new element with value ix
Iterator examples:
auto b = v.begin(), e = v.end(); // begin and end are two iterator members. // Return type is an iterator. # standard container iterator operators # *iter returns a reference to the element denoted by the iterator iter # iter->mem # ++iter # --iter # iter1 == iter2 # iter1 != iter2 string s("some string"); if (s.begin() != s.end()) { // make sure s is not empty auto it = s.begin(); // it denotes the first character in s *it = toupper(*it); // make that character uppercase } // changed the case of the first word in a string to use iterators instead // process characters in s until we run out of characters or we hit a whitespace for (auto it = s.begin(); it != s.end() && !isspace(*it); ++it) *it = toupper(*it); // capitalize the current character # Combining Dereference and Member Access (*it).empty() // dereferences it and calls the member empty on the resulting object # Iterator arithmetic # iter + n # iter -n # iter1 += n iter1 -= n # iter1 - iter2 # >, >=, <, <= // compute an iterator to the element closest to the midpoint of vi auto mid = vi.begin() + vi.size() / 2;
convert a C-style array to a c++ vector
#include <vector> int data[] = { 1, 2, 3, 4, 4, 3, 7, 8, 9, 10 }; std::vector<int> v(data, data+10);
WINVER
http://stackoverflow.com/questions/1439752/what-is-winver WINVER determines the minimum platform SDK required to build your application, which in turn will determine at compile time which routines are found by the headers.
You can use this to verify, at compile time, that your application will work on Windows 2000 (0x0500), for example, or on Windows XP (0x0501).
This was used in win32 disk imager program.
Period
What is the difference between the dot (.) operator and -> in C++?
foo->bar() is the same as (*foo).bar().
Member Access Operators: . and -> from msdn.microsoft.com
Protected vs private members
Private members are only accessible within the class defining them.
Protected members are accessible in the class that defines them and in classes that inherit from that class.
Edit: Both are also accessible by friends of their class, and in the case of protected members, by friends of their derived classes.
Edit 2: Use whatever makes sense in the context of your problem. You should try to make members private whenever you can to reduce coupling and protect the implementation of the base class, but if that's not possible then use protected members. Check C++ FAQ Lite for a better understanding of the issue. This question about protected variables might also help.
alignment of pointers
https://stat.ethz.ch/pipermail/r-devel/2013-August/067314.html
Generate random numbers
- srand(), rand() and RAND_MAX
- How to generate a random number between 0 and 1?
- By default, calling rand() will create same sequence of random numbers on every program run
#include <stdio.h> #include <stdlib.h> int main(void) { // This program will create same sequence of // random numbers on every program run for(int i = 0; i<5; i++) printf(" %d ", rand()); return 0; }
- If you don’t call srand before your first call to rand, it’s as if you had called srand(1) to set the seed to one.
#include <stdio.h> #include <stdlib.h> #include<time.h> int main(void) { for(int i = 0; i<5; i++) printf(" %d ", rand()); printf("\n"); srand(1234); for(int i = 0; i<5; i++) printf(" %d ", rand()); printf("\n"); srand(1); for(int i = 0; i<5; i++) printf(" %d ", rand()); printf("\n"); return 0; } /* output from Ubuntu 16.04 (gcc 5.4.0), CentOS 7 (gcc 4.8.5) or Debian 10 (gcc 8.3.0) 1804289383 846930886 1681692777 1714636915 1957747793 479142414 465566339 961126155 1057886067 1222702060 1804289383 846930886 1681692777 1714636915 1957747793 output from Mac 10.14.5 (Apple LLVM version 10.0.1) 16807 282475249 1622650073 984943658 1144108930 20739838 682106452 895431078 2092213417 933663541 16807 282475249 1622650073 984943658 1144108930 */
- srand() + rand() result is not the same/consistent across platforms. Solutions
- C++11 Mersenne Twister/mt19937. http://www.cplusplus.com/reference/random/mt19937/, examples, cppreference.com.
- http://www.cs.wm.edu/~va/software/park/ as referenced by Running C++ rand and srand on different computers/OS
- If we seed c++11 mt19937 as the same on different machines, will we get the same sequence of random numbers?. Yes. The following example should be corrected by breaking multiple "<<" to separate lines since the order of execution in operator << may depend on the compiler. After I break the line into two, the Ubuntu returns the same result as Mac gives. See also Order of evaluation from cppreference.com.
#include <iostream> #include <random> using namespace std; int main() { mt19937 mt_rand(1234); cout << mt_rand() << ' ' << mt_rand() << endl; return 0; } /* g++ -std=c++11 test.cpp; ./a.out Linux (Ubuntu, Debian, CentOS; do "yum install gcc gcc-c++" first) 2137449171 822569775 Mac, Raspbian armv6l (reverse order compared to Linux) 822569775 2137449171 */
Find sample quantiles (percentiles) using STL
STL algorithms defined in the <algorithm> and <numeric> libraries.
- http://stackoverflow.com/questions/10769743/determine-the-third-quartile-from-a-collection-of-integers-in-c
- http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=290
- http://www.java2s.com/Code/Cpp/STL-Algorithms-Non-modifying-sequence-operations/findanddisplayvinlowest20thpercentile.htm
#include <iostream> #include <numeric> // accumulate #include <algorithm> // std::sort, std::nth_element #include <vector> // std::vector using namespace std; int main() { int grades[]={89, 74, 89, 63, 100}; size_t elements=sizeof(grades)/sizeof(grades[0]); double res= accumulate(grades, grades+ elements, 0)/double(elements); std::cout << "Raw data:"; for(int i=0; i< elements; i++) std::cout << ' ' << grades[i]; std::cout << '\n'; cout << res << " is the mean" << endl << endl; // the iterator constructor can also be used to construct from arrays: std::vector<int> myvector (grades, grades + elements); std::sort(myvector.begin(), myvector.end()); std::cout << "myvector contains:"; for (std::vector<int>::iterator it = myvector.begin(); it!=myvector.end(); ++it) std::cout << ' ' << *it; std::cout << '\n'; double median= *(myvector.begin()+myvector.size()/2); //89 cout<<median << " is the median" << endl << endl; std::vector<int> myvector2 (grades, grades + elements); // None of the elements preceding nth (25-th perct) are greater than it, // and none of the elements following it are less. nth_element(myvector2.begin(), myvector2.begin()+ (int)(myvector2.size()*0.25), myvector2.end()); std::cout << "myvector2 contains:"; for (std::vector<int>::iterator it = myvector2.begin(); it!=myvector2.end(); ++it) std::cout << ' ' << *it; std::cout << '\n'; // This method will select one data as the percentile! int p_25= *(myvector2.begin()+ (int)(myvector2.size()*.25)); cout<<p_25<< " is the 25th percentile" << endl; return 0; }
The output looks like (note in myvector2 data preceding 74 is less than 74 and data following 74 is greater than 74)
$ g++ example.cpp $ ./a.out Raw data: 89 74 89 63 100 83 is the mean myvector contains: 63 74 89 89 100 89 is the median myvector2 contains: 63 74 89 89 100 74 is the 25th percentile $
Calculate execution time
http://stackoverflow.com/questions/5248915/execution-time-of-c-program. The following code is from Programming Arduino Next Steps. It took .04 seconds on Xeon W3690 @ 3.47GHz and 28 seconds on Arduino Uno.
#include <stdio.h> #include <time.h> main() { printf("\nStarting Test\n"); time_t startTime = clock(); // test code here long i = 0; long j = 0; for (i = 0; i < 20000000; i ++) { j = i + i * 10; if (j > 10) j = 0; } // end of test code time_t endTime = clock(); printf("%ld\n", j); // prevent loop being optimized out printf("Finished Test\n"); double timeSpent = (double)(endTime - startTime) / CLOCKS_PER_SEC; printf("seconds taken: %f\n", timeSpent); return 0; }
Time the iterations from 0 to 2147483647
#include <iostream> using namespace std; int main() { /* Purpose: time the iterations from 0 to * the maximum positive integer. * See * http://en.cppreference.com/w/cpp/language/types * http://stackoverflow.com/questions/728068/how-to-calculate-a-time-difference-in-c */ const clock_t begin_time = clock(); int flag=0; for(int i=0; i<2147483647; i++) if (!(i%50)) flag++; std::cout << float( clock () - begin_time ) / CLOCKS_PER_SEC; cout << "\nflag " << flag << endl; int flag2 = 2147483647; cout << "\nflag2=" << flag2 <<endl; flag2++; cout << "\nflag2 + 1=" << flag2 << endl; flag2++; cout << "\nflag2 + 2=" << flag2 << endl; return 0; }
On Xeon(R) CPU E5-1650 0 @ 3.20GHz, it took about 7 seconds and on my UDOO Dual, it took about 1 minute. On Phenom(tm) II X6 1055T, it took 9 seconds. On Raspberry Pi 2, it took 97 seconds. On ODroid xu4, it took 13 seconds.
brb@T3600 /tmp $ g++ tmp.cpp; ./a.out 6.83841 flag 42949673 flag2=2147483647 flag2 + 1=-2147483648 flag2 + 2=-2147483647
execute a command line command from a C++ program
- Use the system() function - http://stackoverflow.com/questions/10931134/return-value-of-system-function-call-in-c-used-to-run-a-python-program
#include <stdlib.h> int main() { system("cp ~/Downloads/testInt.cpp ~/Downloads/testInt2.cpp"); }
- Executing a shell command in c/c++ and getting its output http://en.cppreference.com/w/cpp/utility/program/system
FILE* pipe = popen("your shell command here", "r"); if (!pipe) { cerr<<"popen error"<<endl; } char buffer[128]; while(!feof(pipe)) { if(fgets(buffer, 128, pipe) != NULL){} } pclose(pipe); buffer[strlen(buffer)-1] = '\0';
Check OS
http://stackoverflow.com/questions/142508/how-do-i-check-os-with-a-preprocessor-directive
#ifdef _WIN32 ... #else ... #endif
Check Visual Studio compiler
_MSC_VER macro. See
- https://stackoverflow.com/questions/70013/how-to-detect-if-im-compiling-code-with-visual-studio-2008
- https://msdn.microsoft.com/en-us/library/b0084kay.aspx
- http://www.cplusplus.com/forum/beginner/155465/
- https://github.com/arraytools/C/blob/master/accelerated_unix/chapter03/med.cc
#ifdef _MSC_VER typedef std::vector<double>::size_type vec_sz; #else typedef vector<double>::size_type vec_sz; #endif
Short examples
- How to Find the LCM and GCD of Two Numbers in Multiple Languages
- 11 C++ Code Snippets for Everyday Programming Problems
C libraries
cctype
cerrno
climits
cmath
cstddef
cstdio
cstdlib
http://www.cplusplus.com/reference/cstdlib/
abs(), free(), malloc(), exit(), rand(), system(), getenv(), NULL and some string function.
cstring
ctime
C++ standard libraries
- cppreference.com
- wikipedia
- cplusplus.com
- The C++ Standard Library - A Tutorial and Reference by Nicolai M. Josuttis and reviews from amazon.
STL and c++ standard library
- C++ standard library from wikipedia.
- STL vs C++ standard library. STL was written in the days long before C++ was standardized. Parts of the C++ Standard Library were based on parts of the STL, and it is these parts that many people (including several authors and the notoriously error-ridden cplusplus.com) still refer to as "the STL". However, this is inaccurate; indeed, the C++ standard never mentions "STL", and there are content differences between the two.
Using C and C++ for data science
Using C and C++ for data science - work through a common data science task with C99 and C++11. Printing. Reading data. Fitting data. Plotting. clang++.
Containers
Four categories
- Sequence containers: vector, array, deque, list, forward_list.
- Associative containers: map, set, multimap, multiset.
- Unordered associative containers: unordered_map, unordered_set, unordered_multimap, unordered_multiset.
- Container adaptors: stack, queue, priority_queue.
The most important containers are vector, list and map.
Common operations
See Accelerated C++ 5.9.
container<T>::iterator container<T>::const_iterator container<T>::size_type c.begin() c.end() container<T> c; container<T> c(c2); container<T> c(n); container<T> c(n, t); c=c2; c.size() c.empty() c.insert(d, b, e) c.erase(it) c.erase(b, e); // remove [b, e) c.push_back(t) c[n] // iterator *it (*it).x it->x ++it; b == e; b != e; // string type s.substr(i, j) getline(is, s) s += s2; // vector v.reserve(n) v.resize(n) // list l.sort() l.sort(cmp)
// <cctype> header isspace(c) isalpha(c) isdigit(c) isalnum(c) isupper(c) islower(c) toupper(c) tolower(c)
vector
http://www.cplusplus.com/reference/vector/vector/
push_back() method
http://www.cplusplus.com/reference/vector/vector/push_back/
The vector length does not have to be determined beforehand. The push_back() method can be used to insert an element to the end of a vector object.
clear() method
Removes all elements from the vector (which are destroyed), leaving the container with a size of 0. See http://www.cplusplus.com/reference/vector/vector/clear/.
resize() method
See an application of transform.
Vector of own type
- See Accelerated C++ Chapter 4. See <main2.cc> program which is a standalone program which does not depend on other source. Below it gives an example of the output:
brb@T3600 ~/github/C/accelerated_unix/chapter04 $ ./main2 Taylor 80 90 1 2 3 Jones 90 80 3 2 1 Jones 50.8 Taylor 52.8
size_type
vector<int>::size_type x;
size_type is a (static) member type of the type vector<int>. Usually, it is a typedef for std::size_t, which itself is usually a typedef for unsigned int or unsigned long long.
Declare x as a variable of a type suitable for holding the size of a vector
For example,
string::size_type width(const vector<string>& v) { string::size_type maxlen = 0; #ifdef _MSC_VER for(std::vector<string>::size_type i = 0; i != v.size(); ++i) #else for(vector<string>::size_type i = 0; i != v.size(); ++i) #endif maxlen = max(maxlen, v[i].size()); return maxlen; }
square bracket operator
For example,
const vector<double> v; double d = v[1];
The square bracket operation is actually doing
double d1 = v.operator[](1)
2 dimensional matrix
- http://www.cplusplus.com/forum/articles/7459/
- How to Add and Subtract Two Matrices in C++, Python, and JavaScript
- http://stackoverflow.com/questions/12841170/how-to-define-a-2d-array-in-c-and-stl-without-memory-manipulation
The first example uses resize() method to specify the number of rows and columns.
#include <vector> using std::vector; #define HEIGHT 5 #define WIDTH 3 int main() { vector<vector<double> > array2D; // Set up sizes. (HEIGHT x WIDTH) array2D.resize(HEIGHT); for (int i = 0; i < HEIGHT; ++i) array2D[i].resize(WIDTH); // Put some values in array2D[1][2] = 6.0; array2D[3][1] = 5.5; return 0; }
The second example (Method 2 below) needs to use push_back() twice. So it is probably less efficient.
int main () { /************** 1 2 3 4 5 6 ***************/ // Method 1 const int ROW = 2; const int COL = 3; int array1[ROW][COL]; for(int i=0; i<ROW; i++) for(int j=0; j<COL; j++) array1[i][j] = i*COL+j+1; // Method 2 typedef vector<vector<int> > ARRAY; ARRAY array2; vector<int> rowvector; for(int i=0; i<ROW; i++) { rowvector.clear(); for(int j=0; j<COL; j++) rowvector.push_back(i*COL+j+1); array2.push_back(rowvector); } return 0; }
The first example also works on string type.
#include <iostream> #include <vector> #include <string> using namespace std; void foo1(vector<vector<string>> &vs) { vs.resize(2); for(int i=0; i < 2; ++i) vs[i].resize(4); vs[0][0] = "This"; vs[0][1] = "Is"; vs[0][2] = "A"; vs[0][3] = "BOok"; vs[1][0] = "That"; vs[1][1] = "Is not"; vs[1][2] = "An"; vs[1][3] = "Apple"; } void foo2(vector<vector<string>> &vs) { cout << vs.size() << endl; for(unsigned int i=0; i < vs.size(); ++i) cout << "row " << i << ", size " << vs[i].size() << endl; for(unsigned int i=0; i < vs.size(); ++i) { for(unsigned int j=0; j < vs[i].size(); ++j) { cout << vs[i][j] << " "; } cout << endl; } } int main() { vector<vector<std::string>> vs; foo1(vs); foo2(vs); cout << endl; return 0; }
Comparison of a C++ array and C++ vector
See the example from PPP Chapter 20.1.
double* get_from_jack(int* count); // jack puts doubles into an array // and returns the number of elements in *count vector<double>* get_from_jill(); // Jill fills the vector int main() { int jack_count = 0; double* jack_data = get_from_jack(&jack_count); vector<double>* jill_data = get_from_jill(); // ... Process ... // jack_data[i] ---- value // &jack_data[i] ---- address // // (*jill_data)[i] ---- value, deference the pointer first // &(*jill_data)[i] ---- address, deference the pointer first // // note *jill_data[i] is not what we want; that means *(jill_data[i]) // delete[] jack_data; delete jill_data; } double* get_from_jack(int* count) { if (!count) return 0; const int n = 10; double* arr = new double[n]; if (arr) { *count = n; for (int i = 0; i < n; ++i) arr[i] = i; } return arr; } vector<double>* get_from_jill() { const int n = 10; vector<double>* arr = new vector<double>(n); if (arr) { for (int i = 0; i < n; ++i) (*arr)[i] = i; } return arr; }
list
(From The C++ PL) A list is a double-linked list. We use a list for sequences where we want to insert and delete elements without moving other elements.
(From Acceleted C++) Just as vectors are optimized for fast random access, lists are optimized for fast insertion and deletion anywhere within the container. Because lists have to maintain a more complicated structure, they are slower than vectors if the container is accessed only sequentially. That is, if the container grows and shrinks only or primarily from the end, a vector will outperform a list. However, if a program deletes many elements from the middle of the container, then lists will be faster for large inputs. ... lists and vectors share many operations. As a result, we can often translate programs that operate on vectors into programs that operate on lists, and vice versa.
One key operation that vectors support, but lists do not, is indexing. But if we use 'iterators instead of indices, these two types will be even similar. See 5.5.1 for some important differences between these two.
list<Student_info> extract_fails(list<Student_info>& students) { list<Student_info> fail; list<Student_info>::iterator iter = students.begin(); while (iter != students.end()) { if (fgrade(*iter)) { fail.push_back(*iter); iter = students.erase(iter); } else ++iter; } }
(From The C++ PL) When we use a linked list, we end not to access elements using subscripting the way we do for vectors. Instead, we might search the list looking for an element with a given value.
struct Entry { string name; int number; } list<Entry> phone_book = { {"David Hume", 123456}, {"Karl Popper", 234547}, {"Bert Arthur", 345678} }; int get_number(const string& s) { for (const auto& x : phone_book) if (x.name == s) return x.number; return 0; // use 0 to represent 'number not found' } // OR using the iterator int get_number(const string& s) { for (auto p = phone_book.begin(); p!= phone_book.end(); ++p) if (p->name == s) return p->number; return 0; } // To delete or insert an element void f(const Entry& ss, list<Entry>::iterator p, list<Entry>::iterator q) { phone_book.insert(p, ee); // add ee before the element referred to by p phone_book.erase(q); // remove the element referred to by q }
map
A map is like a vector but using a key instead of an integer to index it (R's vector object can do it already; see An introduction to R).
The following example is from Chapter 7 of Accelerated C++. See also the example and a list of member types/functions from cplusplus.com. The interesting thing is the elements are ordered by their key at all times (see the example below).
#include <iostream> #include <map> #include <string> using std::cin; using std::cout; using std::endl; using std::map; using std::string; int main() { string s; map<string, int> counters; // store each word and an associated counter // read the input, keeping track of each word and how often we see it while (cin >> s) ++counters[s]; // write the words and associated counts for (map<string, int>::const_iterator it = counters.begin(); it != counters.end(); ++it) { cout << it->first << "\t" << it->second << endl; } return 0; }
And the output
brb@T3600 ~/Downloads $ g++ mapTest.cpp brb@T3600 ~/Downloads $ ./a.out this is a book a 1 book 1 is 1 this 1 brb@T3600 ~/Downloads $
array
deque
queue
set
stack
unordered_map
unordered_set
Algorithms
Accelerated C++ 6.4 says Algorithms act on container elements; they do not act on containers. For example, remove_if() and partition() do not change the size of the container on which it operates. The size of the container is the same. To really shorten a vector, we need to use the erase() method from container operations. That is to say, when we use remove() or remove_if() function, it is likely we want to apply erase() method to the container.
/* 6.4 Algorithms, containers and iterators in Accelerated C++ */ students.erase(remove_if(students.begin(), students.end(), fgrade), students.end());
all_of/ any_of/ none_of/ for_each
- http://www.cplusplus.com/reference/algorithm/all_of/
- http://www.cplusplus.com/reference/algorithm/any_of/
- http://www.cplusplus.com/reference/algorithm/none_of/
- http://www.cplusplus.com/reference/algorithm/for_each/
count/ count_if/ find/ find_if/ mismatch/ search/ search_n
N.B.
- string, map and set types also has a member function called find(). See string::find, map::find and set::find.
- Qt has its own solution: QRegExp.
The algorithms find() and find_if() return an iterator to the first element that matches a value and a predicate (bool return type), respectively.
void f(const string& s) { auto p_space = find(s.begin(), s.end(), ' '); auto p_whitespace = find(s.begin(), s.end(), isspace); }
See also the split() function example in 6.1.1 of Accelerated C++ that uses find_if() function.
Example of using std::find() function to return the index of a string (only the first match) in a vector and std::distance to find the distance between two iterators.
#include <algorithm> #include <iostream> #include <vector> // #include <iterator> int main() { int data[] = { 1, 2, 3, 4, 4, 3, 7, 8, 9, 10 }; std::vector<int> v(data, data+10); std::vector<int> indexResult; std::cout << "Original data is "; for(std::vector<int>::iterator it=v.begin(); it != v.end(); ++it) std::cout << *it << " "; std::cout << '\n'; for(std::vector<int>::iterator it=v.begin(); it != v.end(); ++it) { // std::cout << "Begin shift= " << std::distance(v.begin(), it) << ", "; std::cout << "Current data is "; for(std::vector<int>::iterator it2=it; it2 != v.end(); ++it2) std::cout << *it2 << " "; std::cout << ", "; auto p = std::find(it, v.end(), 3); if (p != std::end(v)) std::cout << "element 3 was found in v at position (starting from 0): " << std::distance(it, p) << std::endl; else std::cout << "element 3 was not found in Data\n"; } }
And the output
$ g++ -std=c++11 count.cpp; ./a.out Original data is 1 2 3 4 4 3 7 8 9 10 Current data is 1 2 3 4 4 3 7 8 9 10 , element 3 was found in v at position (starting from 0): 2 Current data is 2 3 4 4 3 7 8 9 10 , element 3 was found in v at position (starting from 0): 1 Current data is 3 4 4 3 7 8 9 10 , element 3 was found in v at position (starting from 0): 0 Current data is 4 4 3 7 8 9 10 , element 3 was found in v at position (starting from 0): 2 Current data is 4 3 7 8 9 10 , element 3 was found in v at position (starting from 0): 1 Current data is 3 7 8 9 10 , element 3 was found in v at position (starting from 0): 0 Current data is 7 8 9 10 , element 3 was not found in Data Current data is 8 9 10 , element 3 was not found in Data Current data is 9 10 , element 3 was not found in Data Current data is 10 , element 3 was not found in Data
But the string type case is more complicated. It only finds the EXACT match string.
#include <algorithm> #include <iostream> #include <vector> #include <string> // #include <iterator> int main() { std::vector<std::string> v = {"x1", "yx12", "x1", "x3", "x4"}; std::vector<int> indexResult; std::cout << "Search position (starting from 0)" << std::endl; std::cout << "Original data is "; for(auto it : v) std::cout << it << " "; std::cout << '\n'; for(std::vector<std::string>::iterator it=v.begin(); it != v.end(); ++it) { std::cout << "Current data is "; for(std::vector<std::string>::iterator it2=it; it2 != v.end(); ++it2) std::cout << *it2 << " "; std::cout << ", "; auto p = std::find(it, v.end(), "x1"); if (p != std::end(v)) std::cout << "element x1 was found in v at position: " << std::distance(it, p) << std::endl; else std::cout << "element x1 was not found in Data\n"; } }
After compiling & running it, we will see the find() function cannot pick up the 2nd case.
$ g++ -std=c++11 count.cpp; ./a.out Search position (starting from 0) Original data is x1 yx12 x3 x4 Current data is x1 yx12 x1 x3 x4 , element x1 was found in v at position: 0 Current data is yx12 x1 x3 x4 , element x1 was found in v at position: 1 Current data is x1 x3 x4 , element x1 was found in v at position: 0 Current data is x3 x4 , element x1 was not found in Data Current data is x4 , element x1 was not found in Data
copy/ copy_if/ swap/ swap_ranges/ remove/ remove_if/ fill/ replace/ replace_if/ shuffle/ unique/ transform
The transform() function is similar to the for_each() function.
An application of transform function is to copy data from the vector to the set and convert that to lowercase. PS. the following example will overwrite the original string because the output iterator is the same as the input iterator.
#include <iostream> #include <algorithm> #include <string> int main() { std::string data = "Abc"; std::transform(data.begin(), data.end(), data.begin(), ::tolower); std::cout << data << std::endl; return 0; }
If the output length is known we can create a new object of the desired size as in this example in cplusplus.com. If the output is unknown, we can use back_inserter() function as in 6.2.3 of Accelerated C++.
Examples of remove_copy() can be found in 6.2.4 of Accelerated C++.
Examples of remove_copy_if() and remove_if() can be found in 6.3.1 of Accelerated C++.
sort/ stable_sort/ is_sorted/ partial_sort
merge/ set_difference/ set_intersection/ set_union
max/ max_element/ min/ min_element/ next_permutation
accumulate/ inner_product/ partial_sum
iterator & sequence
Container ------- Iterator -------- Algorithm
(PPP 20.3 Sequences and iterators) The central concept of the STL is the sequence. From the STL point of view, a collection of data is a sequence.
The reason STL algorithms and containers work so well together is that they don't know anything about each other. Instead, both understand about sequences defined by pairs of iterators.
A sequence has a beginning and an end. We identify the beginning and the end of a sequence by a pair of iterators. An iterator is an object that identifies an element of a sequence. An STL sequence is what is usually called "half-open"; the element identified by begin is part of the sequence, but the end iterator points one beyond the end of the sequence.
What is an iterator?
- An iterator points to an element of a sequence
- You can compare two iterators using == and !=
- You can refer to the value of the element pointed to by an iterator using the unary * operator ("dereference")
- You can get an iterator to the next element by using ++.
- The idea of an iterator is related to the idea of a pointer. However, many iterators are not just pointers; for example, we could define a range-checked iterator that throws an exception if you try to make it point outside its [begin:end) sequence or dereference end. We get enormous flexibility and generality from having iterator as an abstract notion rather than as a specific type.
Advantages of using an iterator
Basic standard iterator operations
// if p and q are two iterators p == q p != q *p *p = val val = *p ++p
Using iterators in string type
auto b=v.begin(), e=v.end(); string s("some string"); for (auto it = s.begin(); it != s.end() && !isspace(*it); ++it) { *it = toupper(*it); // make that char uppercase }
Using iterator in vector type
vector<int>::iterator it; // it can read and write vector<int> elements string::iterator it2; // it2 can read and write characters in a string vector<int>::const_iterator it3; // it3 can read but not write elements string::const_iterator it4; // it4 can read but not write characters vector<int> v; const vector<int> cv; auto it1 = v.begin(); // it1 has type vector<int>::iterator auto it2 = cv.begin(); // it2 has type vector<int>::const_iterator auto it3 = v.cbegin(); // it3 has type vector<int>::const_iterator
Assuming it is an iterator into this vector, we can check whether the string that it denotes is empty as follows:
(*it).empty() # *it.empty() will gives an error
Print each element of a vector of strings.
vector<string> text; for (auto it = text.cbegin(); it != text.cend() && !it->empty(); ++it) cout << *it << endl;
Examples
- split() function (and find_if() library function) in 6.1.1 of Accelerated C++ where the find_if() function is used to find the position of non-space characters (an auxiliary function). Compare with the split() function in Chapter 5 where the search of a new word is done by searching the space key in a while() loop.
- find_urls() function in 6.1.3 of Accelerated C++
numeric
string
utilities
Function objects
pair
Common errors
array out of bound error & memory
- Array index out of bound in C
- How to set memory use limit when writing C program and what happens if once it exceeds this limit?
- ulimit
- ulimit keys
bad_alloc error
http://stackoverflow.com/questions/6833143/how-to-check-memory-allocation-failures-with-new-operator
In C++ there are 2 primary ways in which new allocates memory and each requires different error checking.
The standard new operator will throw a std::bad_alloc exception on failure and this can be handled like a normal exception
try { char* c = new char[100]; } catch (std::bad_alloc&) { // Handle error }
Or alternative the nothrow version of new will simply return NULL on failure
char* c = new (std::nothrow) char[100]; if (!c) { // Handle error }
Debugging
- http://beej.us/guide/bggdb/
- An article from Dr. Dobb's
- The Art of Debugging and Matloff personal website.
- Debugging Tools for Windows (WinDbg, KD, CDB, NTSD)
valgrind
http://valgrind.org/docs/manual/quick-start.html
For example,
valgrind --leak-check=yes build-Qheatmap-Desktop_Qt_4_8_5-Debug/Qheatmap /home/brb/Qt/example/BRCACC/
GDB, DDD, Nemiver
- http://beej.us/guide/bggdb/
- http://calcul.math.cnrs.fr/Documents/Ecoles/PF-2011/Cours/debug_autrans2011.pdf
- http://stackoverflow.com/questions/79023/is-there-a-c-gdb-gui-for-linux
gdb
- http://beej.us/guide/bggdb/ mentioned gdb has a built-in GUI mode called Text User Interface.
- https://en.wikipedia.org/wiki/GNU_Debugger
- http://babbage.cs.qc.edu/courses/cs701/Handouts/using_gdb.html. It mentioned assert(), -DNDEBUG option in g++.
- http://www.cs.umd.edu/~srhuang/teaching/cmsc212/gdb-tutorial-handout.pdf
- https://blogs.oracle.com/ksplice/entry/8_gdb_tricks_you_should
- http://web.stanford.edu/class/cs107/gdb_coredump1.pdf Breakpoints tricks
- http://weldon.whipple.org/technotes/?page_id=33 Breakpoint condition with string
- http://blog.vinceliu.com/2009/07/gdbs-conditional-breakpoints.html Breakpoint condition with string
- http://www.thegeekstuff.com/2014/02/gdb-breakpoins-watchpoints/
A C program with a function: Display Prime Numbers Between Intervals Using Function. A copy of the code is at Github.
To run gdb with its TUI mode,
gcc -g -o foo foo.c gdb -tui foo # Press return key to see the source showing on the top panel
To run a command with arguments, do
gdb --args executablename arg1 arg2 arg3
To combine tui and args parameters, do
gdb -tui --args executablename arg1 arg2 arg3
To run a command with redirect input (e.g. the source code contains e.g. std::cin), do
gdb executablename run < input
file a.out | Load an executable file by name |
---|---|
break hello.c:100 | set a break point (a function, line number) |
break hello.c:100 if i == 5 | set a break point if a condition is true |
cond N Condition | N is the break point number, Condition is any condition (eg i < .5, *p == 'a', strcmp(msg,"OK") == 0) |
info break | |
delete Location | |
clear Location | delete any breakpoints set at or within the code of the specified line |
list | |
run | |
next | |
step | step in |
until | run until the program reaches a source line greater than the current (eg loop) |
finish | Run until the end of the current 'function'. It'll jump back to the caller. |
continue | |
print Expression | |
set Variable=Expression | For example, set x=5 |
backtrace (bt) | #0 is where the code broke. |
frame N | switch to frame N (see backtrace output) |
quit |
ddd
- A Brief Introduction to DDD by knuth.luther.edu.
- To use command line argument, go to Program -> Run where you can specify your command line arguments.
- Check Source -> Display Line Numbers.
- It seems there is not keyboard shorts for ddd. And trying to change the fonts will give you errors.
- A good feature in ddd is once a program aborted, ddd can show the backtrace (Status -> Backtrace...). So it is easy to find out which line of code broke the program and how the line was called. I did not see this feature in Nemiver.
For example,
g++ -Wall -g -o XXX.o -c XXX.cpp g++ -o XXX.exe XXX.o -lstdc++ ddd XXX.exe
nemiver
Nemiver is an on going effort to write an easy to use standalone C/C++ debugger that integrates well in the GNOME environment.
sudo apt-get install nemiver nemiver
- Qt Creator. See the above discussion link for an instruction.
Qt Creator
A screenshot based on Qt Creator 3.3 and Qt 5.4.
Write a Linux Debugger
https://blog.tartanllama.xyz/c++/2017/06/19/writing-a-linux-debugger-source-break/
Tools
Online compilers
- https://wandbox.org for GCC
- http://webcompiler.cloudapp.net/ for VC++
IDE editor
Geany
Pros: show a list of symbols/functions on the left hand side panel. Show the open files as a tree structure on the left hand side. Code folding. Con: the GDB debugger? To install the latest version of geany and geany-plugin-debugger:
sudo add-apt-repository ppa:geany-dev/ppa sudo apt-get update sudo apt-get install geany sudo apt-get install geany-plugin-debugger
Code::Blocks
- http://wiki.codeblocks.org/index.php/Main_Page
- http://wiki.codeblocks.org/index.php/Debugging_with_Code::Blocks
sudo apt-get install codeblocks
Pros: built-in GDB debugger.
This is the one people recommend.
If you have already source code and Makefile. Then
- Put source code together with Makefile under the same directory as ProjectName.cbp file.
- Project->Properties check 'This is a custom Makefile' and modify the makefile name as needed.
- Don't worry about the Execution directory shown there.
- Go to the 'Build targets' tab, change the Output filename to the one we want to run or debug.
- Go to Project->Build Options. Go to "Make" commands tab and change the 'Build project/target:' to $make -f $makefile (i.e. remove $target). This needs to be done for 'Debug' build.
Now we can click the build, run or debug button on the toolbar.
As we can see, the required step to debug an executable in codeblocks is much more complicated than ddd program.
The only thing I want to change is the font of the execution terminal. The font is too small.
Qt Creator
I haven't found a way to use own Makefile to run debugging.
GCC
- http://www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html
- A guide to understanding Linux software libraries in C.
- Static versus dynamic libraries.
- Building the libraries.
- A C library client.
- Wrapping up with a Python client.
Show all libraries used (dynamically linked) by an executable program
Use ldd (List Dynamic Dependencies) command on Linux environment. On Windows OS, we can use Dependency Walker; see this post.
- http://www.cyberciti.biz/tips/linux-shared-library-management.html
- http://www.ibm.com/developerworks/library/l-lpic1-v3-102-3/
- http://qt-project.org/wiki/Show_library_dependencies
- http://www.linuxintro.org/wiki/Ldd
See also the ldconfig command to check if a library is installed or not.
debian@beaglebone:~$ ldd /usr/bin/netsurf libjpeg.so.8 => /usr/lib/arm-linux-gnueabihf/libjpeg.so.8 (0xb6f1c000) libz.so.1 => /lib/arm-linux-gnueabihf/libz.so.1 (0xb6f02000) libxml2.so.2 => /usr/lib/arm-linux-gnueabihf/libxml2.so.2 (0xb6e22000) .... libcurl.so.4 => /usr/lib/arm-linux-gnueabihf/libcurl.so.4 (0xb6dd7000) libtasn1.so.3 => /usr/lib/arm-linux-gnueabihf/libtasn1.so.3 (0xb5d5b000) libp11-kit.so.0 => /usr/lib/arm-linux-gnueabihf/libp11-kit.so.0 (0xb5d47000)
Linking with external libraries
$ gcc -Wall calc.c /usr/lib/libm.a -o calc $ gcc -Wall calc.c -lm -o calc
To specify the library path, we can use "-L", and/or "-Wl,-rpath" in gcc/g++.
When shared libraries are present in nondefault directories, the option "-Wl,-rpath" is needed in linker options. See here. If we don't specify "-Wl,-rpath" in linker options, we need to define "LD_LIBRARY_PATH" environment variable. See an example in RInside.
Header files/Include path
The list of directories for header files is often referred to as the include path, and the list of directories for libraries as the library search path or link path.
When additional libraries are installed in other directories it is necessary to extend the search paths, in order for the libraries to be found. The compiler options -I and -L add new directories to the beginning of the include path and library search path respectively.
$ gcc -Wall -I/opt/gdbm-1.8.3/include -L/opt/gdbm-1.8.3/lib dbmain.c -lgdbm
Environment variables
We can use some environment variables to replace -I and -L flags. See some basic introduction on
- http://www.ntu.edu.sg/home/ehchua/programming/cpp/gcc_make.html
- http://www.network-theory.co.uk/docs/gccintro/gccintro_23.html
Header files (CPATH, C_INCLUDE_PATH, CPLUS_INCLUDE_PATH, OBJC_INCLUDE_PATH)
$ CPLUS_INCLUDE_PATH=/opt/gdbm-1.8.3/include $ export CPLUS_INCLUDE_PATH
Library files during link time
$ LIBRARY_PATH=/opt/gdbm-1.8.3/lib $ export LIBRARY_PATH
Library files during run time (needed only for dynamic libraries). On Windows platform, the PATH variable will be used.
$ export LD_LIBRARY_PATH=/opt/gdbm-1.8.3/lib
Check environment variables
echo $SHELL echo $PATH echo $LIBRARY_PATH env
Makefile
This is an example of <Makefile>. The source code files are Parent.cpp, Parent.h, Child.cpp, Child.h, and main.cpp. Remember the indents should be a single tab.
CC=g++ TARGET=pc OBJECTS=main.o Parent.o Child.o $(TARGET): $(OBJECTS) @echo "** Linking Executable" $(CC) $(OBJECTS) -o $(TARGET) clean: @rm -f *.o *~ veryclean: clean @rm -f $(TARGET) %.o: %.cpp @echo "** Compiling C++ Source" $(CC) -c $(INCFLAGS) $<
'all' and '.PHONY' targets
- (all) http://stackoverflow.com/questions/2514903/makefile-what-does-all-stand-for
- (.PHONY) http://stackoverflow.com/questions/2145590/what-is-the-purpose-of-phony-in-a-makefile. It means the target is NOT a file name.
minimal make
http://kbroman.org/minimal_make/
Autotools
- How to build from source code in GNU/Linux
- http://stackoverflow.com/questions/2531827/what-are-makefile-am-and-makefile-in
Makefile.am is a programmer-defined file and is used by automake to generate the Makefile.in file. The ./configure script typically seen in source tarballs will use the Makefile.in to generate a Makefile.
The ./configure script itself is generated from a programmer-defined file named either configure.ac or configure.in , I prefer .ac (for AutoConf) since it differentiates it from the generated Makefile.in files and that way I can have rules such as make dist-clean which rm -f *.in . Since it is a generated file it is not typically stored in a revision system such as SVN or CVS, rather the .ac file would be.
Read more on GNU build system/Autotools. Read about make and Makefile first, then learn about automake, autoconf, libtool, etc.
CMake
On Windows, it will be installed on C:\Program Files (x86)\Cmake 2.8 folder. By default, it is not added to system PATH. The 'Cmake' program will ask for source, binary folders and the Compiler option. After clicking 'configure' and 'generate' buttons, it will create VS solution file and we can double click the solution file to open the project in Visual Studio. In Visual Studio, we can just build the solution (Ctrl + Shift + B). When we want to debug the code, we should 1. right click on project and select property. Change the working directory to the source code (note that .exe file will be generated there). 2. Set the project as the starting project.
The idea of cmake is it can create <Makefile> file from <CMakeLists.txt> file. See
- https://www.cs.swarthmore.edu/~adanner/tips/cmake.php.
- http://derekmolloy.ie/hello-world-introductions-to-cmake/
For example, if we use git clone to get files from Effective Modern C++.
$ git clone https://github.com/BartVandewoestyne/Effective-Modern-Cpp.git $ cd Effective-Modern-Cpp/Item01_Understand_template_type_deduction $ ls CMakeLists.txt [and other cpp files] $ sudo apt-get install cmake $ mkdir build $ cd build $ cmake .. $ ls MakeCache.txt CMakeFiles cmake_install.cmake Makefile $ make
Profiling
LLVM Compiler Infrastructure and Clang compiler
- clang: a C language family frontend for LLVM
- How to Install a C Compiler on Linux
C++ Libraries
- See Richel Bilderbeek page for more listing.
pthreads - POSIX Threads Programming
- pbzip2 - a parallel implementation of the bzip2 block-sorting file compressor that uses pthreads and achieves near-linear speedup on SMP machines.
- bowtie software which makes use of pthread library. Similar tophat and cuffmerge also have a '-p' argument to support pthread.
Wt
C++ library for developing web applications
SeqAn
C++ for sequencing data. On Windows OS, it requires Python 2 and CMake in addition to VS.
Boost
Boost is a set of C++ libraries for numerical computation that provide support for tasks and structures such as linear algebra, pseudorandom number generation, multithreading, image processing, regular expressions, and unit testing. Release 1.52 contains over eighty individual libraries.
The R library BH provides template use in R. See http://gallery.rcpp.org/articles/using-boost-with-bh/ for a gallery.
Boost contains a lot of libraries.
brb@brb-VirtualBox:~/Downloads/boost_1_56_0$ ./bootstrap.sh --show-libraries Building Boost.Build engine with toolset gcc... tools/build/src/engine/bin.linuxx86/b2 The following Boost libraries have portions that require a separate build and installation step. Any library not listed here can be used by including the headers only. The Boost libraries requiring separate building and installation are: - atomic - chrono - container - context - coroutine - date_time - exception - filesystem - graph - graph_parallel - iostreams - locale - log - math - mpi - program_options - python - random - regex - serialization - signals - system - test - thread - timer - wave
build under Ubuntu OS
To install via apt-get is 'sudo apt-get install libboost-all-dev'. The software center shows the version is 1.48 (kind of old) on Ubuntu 12.04 and 1.54 on Ubuntu 14.04.
We can install it by downloading its source code and build it by ourselves. See this post on ubuntuforums.org.
./bootstrap.sh ./b2 install
At the end of buliding, it will show the paths to header files (sometimes it goes to /usr/local/include) and the libraries themselves (sometimes it is /usr/local/lib). If we use apt-get to install boost, the header files go to /usr/include and the libraries files libboost*.a and libboost*.so go to /usr/lib.
The Boost C++ Libraries were successfully built! The following directory should be added to compiler include paths: /home/brb/Downloads/boost_1_55_0 The following directory should be added to linker library paths: /home/brb/Downloads/boost_1_55_0/stage/lib
The source directory contains <index.html> file. It tells us how to run a simple test program. For example, the following example test headers-only libraries and require no separately-compiled library binaries or special treatment when linking.
g++ -I /home/brb/Downloads/boost_1_55_0 example.cpp -o example echo 1 2 3 | ./example
To link to boost binary libraries, we can do
$ g++ -I /home/brb/Downloads/boost_1_55_0 example.cpp -o example2 \ -L~/Downloads/boost_1_55_0/stage/lib/ -lboost_regex $ ./example2 < jayne.txt Will Success Spoil Rock Hunter?
Note that under boost_1_55_0/stage/lib directory, both static and dynamic libraries are available for boost_regex. My system picks the static library. If we want to link to dynamic library, we can
$ g++ -I /home/brb/Downloads/boost_1_55_0/ example2.cpp -o example2 \ ~/Downloads/boost_1_55_0/stage/lib/libboost_regex.so $ ./example2 < jayne.txt ./example2: error while loading shared libraries: libboost_regex.so.1.55.0: cannot open shared object file: No such file or directory $ export LD_LIBRARY_PATH=/home/brb/Downloads/boost_1_55_0/stage/lib
Here we see the purpose of specifying the environment variable LD_LIBRARY_PATH.
To try an example (Math and numerics > math/statistical distributions > Calculating confidence intervals on the mean with the Students-t distribution), we can compile and generate the executable file by (no need to link to library in this case)
g++ -I /home/brb/Downloads/boost_1_55_0/ \ ~/Downloads/boost_1_55_0/libs/math/example/students_t_single_sample.cpp
If we like the headers and libraries automatically available in linux environment without using -I and -L parameters in g++, we can run
./bootstrap.sh --prefix=/usr/local sudo ./b2 install
Running ./b2 took about 1 hours on my single core VM. At the end, it will create /usr/local/include/boost subdirectory and a bunch of libboost*.a and libboost*.so will be created under /usr/local/lib directory.
Check BOOST version
- On Ubuntu, use ' tail /usr/include/boost/version.hpp'
- IN boost C++ code, use boost version macro 'BOOST_LIB_VERSION'
#include <boost/version.hpp> #include <iostream> using namespace std; int main() { cout << "Boost version: " << BOOST_LIB_VERSION << endl; return 0; }
Build boost from source on Windows OS
- http://andres.jaimes.net/718/how-to-install-the-c-boost-libraries-on-windows/
- http://www.rodneybeede.com/Boost_C___libraries_on_Windows_with_MinGW.html
- http://www.boost.org/doc/libs/1_55_0/more/getting_started/windows.html
MinGW
boostrap --with-toolset=gcc .\b2 --build-type=complete toolset=gcc link=shared runtime-link=shared install
use of statistical distributions in Boost
See an article in www.quantnet.com
For each of distribution functions, we can compute cdf, quantile, pdf, mean, mode, median, variance, etc.
To compute t(alpha/2, df), we can
#include <boost/math/distributions/students_t.hpp> #include <iostream> using namespace std; using boost::math::students_t; int main() { int df = 195; double alpha = .1; students_t dist(df); double T = quantile(complement(dist, alpha / 2)); cout << T << endl; return 0; }
We can compile the code and get the result (check by using R statement qt(.95, 195)).
$ g++ example.cpp; ./a.out 1.65271
PS For some reason, I don't need to worry about environment variable.
Googling shows we can use g++ --print-search-dirs to show LIBRARY search paths and adding -v to show include search paths to g++ command.
Boost thread example
http://ashishgrover.com/boost-multi-threadingfor-c/
#include <boost/thread.hpp> void readerApi() { for (int i=0; i < 10; i++) { usleep(400); std::cout << "readerApi: " << i << std::endl; } } void writerApi() { for (int i=0; i < 10; i++) { std::cout << "writerApi: " << i << std::endl; usleep(400); } } int main() { boost::thread readerThread(readerApi); boost::thread writerThread(writerApi); readerThread.join(); writerThread.join(); }
Then compile the code by
$ g++ -o b1 boost1.cpp -lboost_thread
Before you can run it, specify LD_LIBRARY_PATH env variable if you build boost library by yourself.
$ export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH $ ./b1 writerApi: 0 readerApi: 0 writerApi: 1 readerApi: 1 writerApi: 2 readerApi: 2 writerApi: 3 writerApi: 4 readerApi: 3 writerApi: 5 readerApi: 4 writerApi: 6 readerApi: 5 writerApi: 7 readerApi: 6 writerApi: 8 readerApi: 7 writerApi: 9 readerApi: 8 readerApi: 9
To make changes permanent in Ubuntu you have to add a new configuration file for ldconfig:
sudo nano /etc/ld.so.conf.d/libboost.conf
(my editor of choice is nano, and the name of the file itself doesn’t matter) Add the library path to that file, i.e. /usr/local/lib/. Save the file, quit and reload your configuration by calling
sudo ldconfig
Note that your LD_LIBRARY_PATH won’t change, but your program will now run!
Another working example is from http://www.codeproject.com/Articles/279053/How-to-get-started-using-Boost-threads
#include <iostream> #include <boost/thread.hpp> #include <boost/date_time.hpp> void workerFunc() { boost::posix_time::seconds workTime(3); std::cout << "Worker: running" << std::endl; // Pretend to do something useful... boost::this_thread::sleep(workTime); std::cout << "Worker: finished" << std::endl; } int main(int argc, char* argv[]) { std::cout << "main: startup" << std::endl; boost::thread workerThread(workerFunc); std::cout << "main: waiting for thread" << std::endl; workerThread.join(); std::cout << "main: done" << std::endl; return 0; }
It can be built by g++ test.cpp -lboost_thread -lboost_system.
Another excellent example is from Jeff Benshetler. Check out this page http://advancedcplusplus.com/5min-threads/ (I cannot build it successfully).
Books
- The Boost C++ Libraries by Boris Schäling Online ebook from an old version of the book and Amazon
- Boost C++ Application Development Cookbook
Boost and Rcpp package
Boost.python
http://edyfox.codecarver.org/html/boost_python.html
Rcpp was inspired by Boost.python. See the Rcpp module vignette.
The Scythe Statistical Library
Scythe: An Open Source C++ Library for Statistical Computation from J of Stat Software.
Armadillo
Armadillo is a C++ linear algebra library (matrix maths) aiming towards a good balance between speed and ease of use.
GNU Scientific Library
BLAS, LAPACK
IMSL
Numerical Recipes
Some C++ Projects
Approximate nearest neighbor search
The R wrap is here
BEDTools
https://github.com/arq5x/bedtools2
freebayes
https://github.com/ekg/freebayes/
NGS++
A programming library in C++11 specialized in manipulating both next-generation sequencing (NGS) datasets and genomic information files. See the paper.
LIBSVM
SAMTools (in C only)
Tophat
It also requires the packages
- Boost
- SamTools and its source code
Salmon - fast and bias-aware quantification of transcript expression
http://www.rna-seqblog.com/salmon-fast-and-bias-aware-quantification-of-transcript-expression/
Parana2
It also depends on a few other tools.
- Bio++ - a set of C++ libraries for Bioinformatics, including sequence analysis, phylogenetics, molecular evolution and population genetics.
- Boost
- GMP - The GNU Multiple Precision Arithmetic Library
- MPFR - C library for multiple-precision floating-point computations with correct rounding.
- pugixml - light-weight C++ XML processing library.
Comprehensive short read mapping
Short read alignment with populations of genomes
https://github.com/viq854/bwbble
Janus-comprehensive tool investigating the two faces of transcription
It depends on bamtools.
Rcount-simple and flexible RNA-Seq read counting
- Paper
- https://github.com/MWSchmid/Rcount (based on C++ and Qt)
RSEM/RNA-Seq by Expectation-Maximization
RNA-Pareto
Interactive Analysis of Pareto-optimal RNA Sequence-Structure Alignments
The software is written in Java 6 (graphical user interface) and C++ (dynamic programming algorithms). To run, a Java Runtime Environment, version ≥1.6.0 is required. It is well tested with GCC 4.6.
ANGSD
Analysis of Next Generation Sequencing Data
Open MS
http://open-ms.sourceforge.net/. It used external libraries such as: (i) Qt, which provides visualization and database support; (ii) Xerces for XML file parsing; (iii) libSVM, for machine learning algorithms; and (iv) the GNU Scientific Library (GSL), used for mathematical and statistical analysis. One of the strong points of OpenMS is a complete set of examples to extend and use the libraries, the TOPP (The OpenMS Proteomics Pipeline) and TOPPView tutorials describe in detail the OpenMS.
MACAU - Differential Expression Analysis for RNAseq using Poisson Mixed Models
http://www.xzlab.org/software.html. GSL and Lapack are used.
GUI Programming
Windows Programming
Resource
- http://www.stanford.edu/class/cs193w/
- Petzold Programming Windows 1998 with source code for download
- Kruglinski Programming Microsoft Visual C++, 1998
- Xoax which contains tutorials for C++, OpenGL, Win32 C++ and more.
- ProgrammingKnowledge about Visual C++ Windows Forms Application Tutorial in Youtube.
- Simple GUI calculator using VS C++/CLR
Difference between Win32 project and CLR (common language runtime) project
See here.
A Win32 project is used if you want to end up with a DLL or a Win32 application usually using the bare WinAPI. A CLR project is used to create C++/CLI project, i.e. to use C++/CLI to target the .NET platform.
The main difference between projects is what Visual Studio comes up with in terms of pre-created files. A windowed Win32 application for example (what you get when you choose Win32 project, but not a DLL) is created with a file for resources (menus, acceleators, icons etc.) and some default code to create and register a window class and to instantiate this window.
Quoted from http://en.wikipedia.org/wiki/Common_Language_Runtime
The Common Language Runtime (CLR) is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as Just-in-time compilation, the compiled code is converted into machine instructions that, in turn, are executed by the computer's CPU. The CLR provides additional services including memory management, type safety and exception handling. All programs written for the .NET framework, regardless of programming language, are executed by the CLR. It provides exception handling, garbage collection and thread management. CLR is common to all versions of the .NET framework.
The CLR is Microsoft's implementation of the Common Language Infrastructure (CLI) standard.
Difference between Win32, MFC and .NET
Using the CLR will provide you with the most expressive set of libraries (the entire .NET framework), at the cost of restricting your executable to requiring the .NET framework to be installed at runtime, as well as limiting you to the Windows platform (however, all 4 listed technologies are windows only, so the platform limitation is probably the least troublesome).
However, CLR requires you to use the C++/CLI extensions to the C++ language, so you'll, in essense, need to learn some extra language features in order to use this. Doing so gives you many "extras," such as access to the .net libraries, full garbage collection, etc.
Using Win32 directly provides the smallest executables, with the fewest dependencies, but is more work to write. You have the least amount of helper libraries, so you're writing more of the code.
Win32 is the raw, bare-metal way of doing it. It's tedious, difficult to use, and has alot of small details you need to remember otherwise things will fail in relatively mysterious ways.
MFC builds upon Win32 to provide you an object oriented way of building your application. It's not a replacement for Win32, but rather an enhancement - it does alot of the hard work for you.
System.Windows.Forms (which is what I assume you meant by CLR) is completely different, but has large similarities to MFC from its basic structure. It's by far the easiest to use, but requires the .NET framework, which may or may not be a hindrance in your case.
Why not MFC
http://win32-framework.sourceforge.net/explanation.htm The website also provides an alternative software called Win32++ to replace MFC. It also provides useful links for C++ compilers, tools, tutorial and references.
Qt
- C++ GUI Programming with Qt 4
- Qt Graphics http://qt-project.org/doc/qt-5.0/qtdoc/topics-graphics.html
- 2D Painting Example QPainter and QGLWidget can be used together to display accelerated 2D graphics on supported hardware. OpenGL examples are here.
wxwidgets
Some projects:
Simple OpenGL GUI
As mentioned in http://www.oppi.uef.fi/bioinformatics/forg3d/downloads.php
OpenGL Programming on Windows
We need to include
#include <gl/gl.h> #include <gl/glu.h>
And go to project's link properties and enter <opengl32.lib> & <glu32.lib>. Check the directory C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Include and C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\lib
header files are: gl\gl.h and glu.h libraries are: openGL32.lib and GLU32.lib
x64 libs can be found in C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\lib\x64 you can put freeglut lib and header files to those locations to use freeglut with visual studio 2010 when you copy freeglut DLLs to C:\Windows\System32 don’t copy 64 bit DLL to syswow64 this gives a freaky error 0xc000007b when running code. Don’t know what it mean, but if you have freeglut only in system32 you going to be fine.
Resource
- [Book] OpenGL Programming Guide: The Official Guide to Learning OpenGL. Online book ver 1.1
- http://nehe.gamedev.net/
- http://homepage.cs.uiowa.edu/~cwyman/classes/common/howto/winGLUT.html. The instruction there assumes the Windows XP. On my Windows 7 and VS2010 machine, I see <glu32.lib> in C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\Lib.
- http://www.cprogramming.com/tutorial/opengl_first_opengl_program.html
- http://www.devshoe.net/2012/08/opengl-programming-in-windows-7-64-bit.html
- http://www3.ntu.edu.sg/home/ehchua/programming/opengl/HowTo_OpenGL_C.html (Notice the comment at the end)
- http://www.opengl-tutorial.org/beginners-tutorials/tutorial-1-opening-a-window/
- OpenGL on Windows
- http://www.nullterminator.net/opengl32.html (hmv, without using glut). See also a discussion on here why it is platform specific to initialize OpenGL.
- Check OpenGL version: glview
- Setting up freeGLUT on Visual Studio 2010
- Google: windows opengl programming tutorial visual studio
Example 1
http://openglbook.com/setting-up-opengl-glew-and-freeglut-in-visual-c/
- Download freeglut (freeglut-MSVC-2.8.0-1.mp.zip) & glew (glew-1.9.0-win32.zip)
- Copy files include and lib to appropriate location
- Copy freeglut.dll to the Project's Release or Debug folder
I don't need Step 5 (Compiler) and Step 6 (Linker).
I keep a copy of the instruction in Evernote.
Example 2
Teapot and Glut shapes (WireTeapot, SolidTeapot, SolidCube & SolidSphere) from http://openglsamples.sourceforge.net/
Example 3 (no Glut, Windows OS only)
http://www.nullterminator.net/opengl32.html
Examples from opengl.org
http://www.opengl.org/sdk/docs/tutorials/
Example of American Flag
http://www.youtube.com/watch?v=9xjBlde4Cew