C Program to find the sum of digits of a number using recursion

Write a C Program to find the sum of digits of a number using recursion.

  #include <stdio.h>
  #include <string.h>

  /* sum of digits of the given number */
  void sumOfDigits(int num, int *sum) {
        /* finds sum of digits */
        if (num) {
                *sum = *sum + num % 10;

                /* recursive call */
                sumOfDigits(num / 10, sum);
        }
        return;
  }

  int main() {
        int num, sum = 0;

        /* get the input value from the user */
        printf("Enter your input value:");
        scanf("%d", &num);

        /* sum of digits of the given input */
        sumOfDigits(num, &sum);

        /* print the sum of digits of the given input */
        printf("Sum of digits of %d is %d\n", num, sum);

        return 0;
  }

  Output:

  jp@jp-VirtualBox:~/$ ./a.out
  Enter your input value:123456
  Sum of digits of 123456 is 21