9.48.2.1 Special Characters ........................... '#' is the line comment character. If a '#' appears as the first character of a line, the whole line is treated as a comment, but in this case the line can also be a logical line number directive ( Comments) or a preprocessor control command (Preprocessing). Two dashes ('--') can also be used to start a line comment. The ';' character can be used to separate statements on the same line.