isxdigit -- Hexadecimal Digit Test

SYNOPSIS
#include <ctype.h>
int isxdigit(int c);
DESCRIPTION
isxdigit
tests an integer value c
to determine whether it is a
hexadecimal digit (uppercase or lowercase).
RETURN VALUE
isxdigit
returns 0 if the character is not a hexadecimal digit, or a
nonzero value if it is. If the argument is EOF
, 0 is returned.
CAUTION
The effect of isxdigit
on a noncharacter argument other than
EOF
is undefined. Do not assume that isxdigit
returns
either 0 or 1.
EXAMPLE
#include <ctype.h>
#include <stdio.h>
#define IDLEN 40
main()
{
char line[IDLEN];
char id[IDLEN+1];
char *text;
int i;
puts("Enter a string consisting of hexadecimal characters: ");
text = gets(line);
/* Copy from text to id. */
for (i = 0; i < IDLEN ; ++i) {
if (isxdigit(text[i]))
id[i] = text[i];
else
id[i] = '*';
}
id[i] = '0';
/* All nonhex characters have been replaced by '*'. */
puts("You have entered the following hexadecimal characters:");
printf("%sn", id);
}
RELATED FUNCTIONS
isdigit
SEE ALSO
Character Type Macros and Functions