a recursive function that calculates the sum of all digits
#include <stdio.h>
int SumOfDigits(int);
int main()
{
int num;
printf("enter the number: ");
scanf("%d",&num);
printf("the sum of all digit is %d",SumOfDigits(num));
return 0;
}
int SumOfDigits(int num)
{
if(num==0) //basic condition
return 0;
else
return num%10 + SumOfDigits(num/10); //recursive procedure
}