#include <stdio.h>

/* Example program provided by Dr. Christie Ezeife  */
 /* The simple program finds the sum of any two given
           integer numbers using one function with call-by-reference
          parameters for all function results but
         call-by-value parameters for all function actual input values.
        */


/* I declare the function prototype here */
void FindSum(int, int, int *);

int main(void)
{

	int Num1, Num2, Sum;

	printf("Type the two numbers to add: e.g. 45 20 \t:");
	scanf("%d  %d", &Num1, &Num2);

	/* Here, I should call the function FindSum to get the Sum */
	/* Note the function passes the address of Sum through 
	  call-by-reference and this permits the function to access 
	  Sum to change the result value. 
	  The actual parameters of the FindSum are Num1, Num2, &Sum */

	FindSum(Num1, Num2, &Sum);

	printf("%d  + %d = %d \n", Num1, Num2, Sum);

        return  0;
}  /* end of Main  */

/* Now, I should define the function FindSum specifying its */
/* formal parameters, which are integers N1, N2, int *Sump   */

void FindSum(int N1, int N2, int *Sump)
{

	/* For pointer variable used to store an address, we can access 
	  content at this address to change its value using * indirection 
	  operator as seen below.				*/

	*Sump = N1 + N2;

}   /*  end of function definition for FindSum */