/* File: perfect-driver-2.cpp ------------------------------------------------
 * Prints the perfect numbers between 1..1000.
 * Defines sumOfDivisors() and isPerfect() as void-valued functions.
 * 
 * NOTE: This program has a bug. Insert scaffolding to find it, and
 * eliminate it.
 */

#include <iomanip.h> //for setw, setprecision, fixed, floatfield, showpoint 

void sumOfDivisors(int n, int& result);     
void isPerfect(int n, int& result);

/* main() ----------------------------------------------------------
 */
void main(){
  int ans;   //answer; result of calling isPerfect()

  cout << "Perfect numbers 1..1000: "; 
  //generate and test each value of n
  for(int n = 2; n <= 1000; n++){
    //test: is n perfect?
    isPerfect(n, ans);
    if(ans)
      cout << setw(5) << n;
  }
  cout << endl << "Exiting.." << endl;
}

/* sumOfDivisors() -------------------------------------------------
* result is the sum of the proper divisors of n (excluding n)
*/
void sumOfDivisors(int n, int& result){
   int pd = 2,     //potential divisor
       sum = 0;    //sum of divisors
   //sum divisors of n
   while(pd <= (n / 2)){
     if((n % pd) == 0)
       sum += pd;
     pd++;
   }
   //return results
   result = sum;
}

/* isPerfect() -------------------------------------------------
* result is true if n is a perfect number
*/
void isPerfect(int n, int& result){
   int sod;   //sum of divisors
   //assign correct value to sod
   sumOfDivisors(n, sod);
   //return result
   result = (sod == n);
}