Usage and example of C library function isxdigit()

C Standard Library <ctype.h>

The isxdigit() function checks if a character is a hexadecimal digit character (0-9, af, AF).

The function prototype of isxdigit() is:

int isxdigit(int arg);

It is<ctype.h>Defined in the header file.

isxdigit() parameter

The isxdigit() function takes a single character as a parameter.

Note:In C programming, characters are internally treated as int values.

C isxdigit() return value

If the argument passed to isxdigit() is

• Hexadecimal character, isxdigit() returns a non-zero integer.

• Non-hexadecimal character, isxdigit() returns 0.

Example1C isxdigit() function

#include <ctype.h>
#include <stdio.h>
int main() {
　　　char c = '5';
　　　int result;
　　　//Passing a hexadecimal character
　　　result = isxdigit(c);　//　Result is not zero
　　　printf("When %c is passed to isxdigit(): %d", c, isxdigit(c));
　　　c = 'M';
　　　//Non-hexadecimal character passed
　　　result = isxdigit(c);　//　result is 0
　　　printf("\nWhen %c is passed to isxdigit(): %d", c, isxdigit(c));
　　　return 0;
}

Output Result

When　5　Result when passed to isxdigit():　128
Result when M is passed to isxdigit(): 0

Example2Program to check hexadecimal characters

#include <ctype.h>
#include <stdio.h>
int main() {
　　　char c = '5';
　　　printf("Enter a character: ");
　　　c = getchar();
　　　if (isxdigit(c) != 0) {}}
　　　　　　printf("%c is a hexadecimal character.", c);
　　　} else {
　　　　　　printf("%c is not a hexadecimal character.", c);
　　　}
　　　return 0;
}

Output Result

Enter a character: f
f is a hexadecimal character.

C Standard Library <ctype.h>