Sum of digit of a number using recurrsion function

#include<stdio.h>
#include<conio.h>
void main()
{
int sumdig(int);
int n,sum,d,f,rev=0;
clrscr();
printf("enter the number");
scanf("%d",&n);
sum=sumdig(n);
printf("%d",sum);
getch();
}

int sumdig(int n)
{
int sum,d,r=0;
if(n==0)
return(0);
else
sum=n%10+sumdig(n/10);
while(sum!=0)
{
d=sum%10;
r=r+d;
sum=sum/10;
}
return(r);
}