### # (Null) Preprocessor Directive

The null directive performs no action. It consists of a single # on a line of its own.

The null directive should not be confused with the # operator or the character that starts a preprocessor directive.

In the following example, if `MINVAL` is a defined macro name, no action is performed. If `MINVAL` is not a defined identifier, it is defined 1.

>     #ifdef MINVAL
>       #
>     #else
>       #define MINVAL 1
>     #endif

Preprocessor Directives

List of Preprocessor Directives