3.11 isxdigit—hexadecimal digit predicate

Synopsis

     #include <ctype.h>
     int isxdigit(int c);
     

Description
isxdigit is a macro which classifies ASCII integer values by table lookup. It is a predicate returning non-zero for hexadecimal digits, and 0 for other characters. It is defined only if c is representable as an unsigned char or if c is EOF.

You can use a compiled subroutine instead of the macro definition by undefining the macro using `#undef isxdigit'.

Returns
isxdigit returns non-zero if c is a hexadecimal digit (0–9, a–f, or A–F).

Portability
isxdigit is ANSI C.

No supporting OS subroutines are required.