isxdigit() function in C Language

isxdigit() function in C programming language checks that whether the given character is hexadecimal or not. isxdigit() function is defined in ctype.h header file. Hexadecimal equivalent of Decimal Numbers:

Hexadecimal: 0   1   2   3    4   5    6   7    8   9    A    B       C      D    E     F
Decimal:    0   1    2   3    4   5    6   7    8   9    10   11    12     13    14    15

Syntax:

char isxdigit( char x);

Examples:

Input : A
Output : Entered character is hexadecimal
Input : 2
Output : Entered character is hexadecimal
Input : @
Output : Entered character is not hexadecimal

// C program to demonstrate isxdigit()
#include <ctype.h>
#include <stdio.h>

int main()
{
    // taking input
    char ch = 'A';

    // checking is the given input is hexadecimal or not?
    if (isxdigit(ch))
        printf("\nEntered character is hexadecimal");
    else
        printf("\nEntered character is not hexadecimal");
}

Output:

Entered character is hexadecimal

Application : isxdigit() function in C programming language is used to find out total numbers of hexadecimals present in any given input. Example:

Input: abc123
Output: Number of hexadecimals present in the given input is : 6
Input: abcdef
Output: Number of hexadecimals present in the given input is : 6
Input: 123456@$
Output: Number of hexadecimals present in the given input is : 6

Let's see C program on this topic: 

// C program to demonstrate isxdigit()
#include <ctype.h>
#include <stdio.h>

int ttl_hexadecimal(int i, int counter)
{
    char ch;
    char a[50] = "@#asf12345";
    ch = a[0];

    // counting of hexadecimal numbers
    while (ch != '\0') {
        ch = a[i];
        if (isxdigit(ch))
            counter++;

        i++;
    }

    // returning total number of hexadecimal
    // in the given input
    return (counter);
}

int main()
{
    int i = 0;
    int counter = 0;
    counter = ttl_hexadecimal(i, counter);

    printf("\nNumber of hexadecimals in string"
             " is : %d", counter);
    return 0;
}

Output:

Number of hexadecimals in string is : 7