///////////////////////////////////////////////////////////////
//  interest.cpp - interest calculator                       //
//  Jim Fawcett, Instructor, CRI In-Plant Course, S'99       //
//  build: cl /GX interest.cpp                               //
///////////////////////////////////////////////////////////////

#include <iostream>
using namespace std;

void main() {

  cout << "\n  Interest Calculator  "
       << "\n =====================\n\n";

  double loanValue;  
  double interest;
  unsigned int numYears;
  cout << "  loan value ($), interest (%), years: (0 0 0 to quit)\n";
  cout.setf(ios::fixed,ios::floatfield);  // use fixed notation
  cout.precision(2);                      // two digits after decimal
  while(1) {
    cout << "? ";
    cin  >> loanValue >> interest >> numYears;
    double numMonths = 12*numYears;
    if(loanValue <= 0)
      break;
    double sum = 0;
    double factor = 1;
    int n;
    for(n=0; n<numMonths-1; n++) {
      sum = sum + factor;
      factor = factor*(1 + interest/(12*100.0));
    }
    double payments = loanValue*factor/sum;
    double cost = payments*numMonths;
    cout << "  payment = " << payments << ", total cost = " 
         << cost << endl;
  }
}