Calculate sum of digits using a function.

#include <stdio.h>

int sod(long int);

int main(void)
{
long int num;
int sum;

printf("\nEnter num : ");
scanf("%ld", &num);

sum = sod(num);

printf("\nSum of digits of %ld is %d", num, sum);

return 0;
}

int sod(long int num)
{
int s = 0;

while(num > 0)
{
s += (num % 10);
num /= 10;
}

return s;
}