Source code is treated during preprocessing and compilation as a sequence of tokens. There are five different types of tokens:
Adjacent identifiers, keywords and literals
must be separated with white space. Other tokens should be
separated by white space to make the source code more readable.
White space includes blanks, horizontal and vertical tabs, new
lines, form feeds and comments.
Lexical Elements of C -
Comments
Lexical Elements -
Identifiers
Lexical Elements -
Constants