C Program for Sum of digits using recursive function

Below program first accept the positive number from user and then find out the sum of digits. for example if user enter 234 then sum of digit is 2+3+4 = 9

//Program Name: Write a function for Sum Of digits
// for example if user enter 121 then sum of digit is 1+2+1 = 4

#include<stdio.h>
#include<conio.h>
int sum_d(int n)
 {
    if(n==0)
       return(0);
    else
      return(n%10+sum_d(n/10));
 }//end of function

void main()
{     int no,sum;

      printf("\n\tEnter a number to calculate digit sum:\t ");
      scanf("%d",&no);

       sum=sum_d(no);

      printf(" \n\n\tSum of digit is =\t %d ",sum);

}//end of main

Output

        Enter a number to calculate digit sum:   543
 

        Sum of digit is =        12


        Enter a number to calculate digit sum:   2
 

        Sum of digit is =        2