9.41.3.1 Special Characters ........................... The presence of a '#' appearing anywhere on a line indicates the start of a comment that extends to the end of that line. If a '#' appears as the first character of a line then 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). The ';' character can be used to separate statements on the same line.