Token : identifiers, keywords, constants, string literals, operators and other separators.
If the input stream has been separated into tokens up to a given character, the next token is the longest string of characters that could constitute a token.
Comment :/* comment */
Integer Constant: Sequence of digits is taken to be octal if it begins with 0, decimal otherwise. A sequence of digits preceded by 0x or 0X is taken to be a hexadecimal integer. An integer constant may be suffixed by the letter u or U, to specifiy that it is unsigned. It may also be suffixed by the letter l or L to specify that it is long.