C program to add numbers using call by reference

#include <stdio.h>
 
long add(long *, long *);
 
int main()
{
   long first, second, *p, *q, sum;
 
   printf("Input two integers to add\n");
   scanf("%ld%ld", &first, &second);
 
   sum = add(&first, &second);
 
   printf("(%ld) + (%ld) = (%ld)\n", first, second, sum);
 
   return 0;
}
 
long add(long *x, long *y) {
   long sum;
 
   sum = *x + *y;
 
   return sum;
}

Output of program:

Input two integers to add 

4

5

4+5=9