/*FUNCTION<<isxdigit>>---hexadecimal digit predicateINDEXisxdigitANSI_SYNOPSIS#include <ctype.h>int isxdigit(int <[c]>);TRAD_SYNOPSIS#include <ctype.h>int isxdigit(int <[c]>);DESCRIPTION<<isxdigit>> is a macro which classifies ASCII integer values by tablelookup.  It is a predicate returning non-zero for hexadecimal digits,and <<0>> for other characters.  It is defined only when<<isascii>>(<[c]>) is true or <[c]> is EOF.You can use a compiled subroutine instead of the macro definition byundefining 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.*/#include <_ansi.h>#include <ctype.h>#undef isxdigitint_DEFUN(isxdigit,(c),int c){	return((_ctype_ + 1)[c] & ((_X)|(_N)));}