Compiler

Lexical Analysis

  if (i == j)
    z = 0;
  else
    z = 1;

is indeed below in computers

\tif (i == j)\n\t\tz = 0;\n\telse\n\t\tz = 1;

Token Class

Identifier, keywords, '(', ')', Numbers, ...

• Token classes correspond to sets of strings.
• Identifier: A1, Foo, B17
• Integer: 0, 99
• Keyword: 'else' or 'if' or 'begin' or ...
• Whitespace: if___else

• Classify program substrings according to role
• Communicate tokens to the parser

                                 Token    
   string ---> Lexical Analysis -------> Parser

Resource

• coursera.org