@c ----------------------------------------------------------------------
@node isxdigit, ctype
@subheading Syntax

@example
#include <ctype.h>

int isxdigit(int c);
@end example

@subheading Description

Tells if @var{c} is a valid hexadecimal digit or not.  This includes
@code{[0-9a-fA-F]}. 

@subheading Return Value

Nonzero if @var{c} is a hex digit, else zero.


@subheading Portability

@portability ansi, posix