Sum of digits

Write a program to calculate sum of digits.

#include<stdio.h>
int Sum_of_Digits(int);
int main()
{
	int num;
	//int s;
	printf("Enter Number = ");
	scanf("%d",&num);
	if(num > 0)
		printf("Sum of Digits of a Number %d is = %d\n",num,Sum_of_Digits(num));
	else
		printf("Sum of Digits of a Number %d is = %d\n",num,Sum_of_Digits(-num));
	//for(s=0;num;s = s + num%10,num=num/10);
	return 0;
}
int Sum_of_Digits(int n)
{
	int sum = 0;
	while(n)
	{
		sum = sum + n % 10;
		n = n/10;
	}
	return sum;
}

Output

Enter Number = 1234
Sum of Digits of a Number 1234 is = 10