Sum of digits using recursion in C program

//sum of digit using recursion
#include <stdio.h>

int sum (int a);

int main()
{
int num, result;

printf("Enter the number: ");
scanf("%d", &num);
result = sum(num);
printf("Sum of digits in %d is %d\n", num, result);
return 0;
}

int sum (int num)
{
if (num != 0)
{
return (num % 10 + sum (num / 10));
}
else
{
return 0;
}
}