// THIS PROGRAM CALCULATE THE NUMBER OF MONTHS NEEDED TO PAYOFF A LOAN 
// AND THE AMOUNT OF INTEREST PAID ON THE LOAN.
//
// Written by Hosung Leo Kim


#include <iostream>
#include <cstdlib>

using namespace std;


int main()
{
  float loan = 1000;
  float monthlyPayment = 50;
  float monthlyRate = 0.015;
  float debt;
  float towardLoan;
  float monthlyInterest; 
  float monthlyInterestSum = 0;
  int   month = 0;
  
  cout.setf( ios::fixed );
  cout.setf( ios::showpoint );
  cout.precision( 2 );
  

  cout << "The total amount of the loan? ";
  cin >> loan;
  
  cout << "The monthly payment? ";
  cin >> monthlyPayment;
  
  cout << "The monthly interest rate? ";
  cin >> monthlyRate;
  

  // THE MONTHLY PAYMENT SHOULD LARGE ENOUGH TO PAY OFF
  // THE MONTHLY INTEREST AND SOME OF THE DEBT.
  if ( ( loan * monthlyRate ) >= monthlyPayment )
  {
    cout << "The monthly payment is NOT large enough to payback the loan. Bye."
         << endl;
    exit(1);
  }

  
  debt = loan;


  while ( true )
  {
    month++;
    cout << "Month #" << month << ": ";
  
    monthlyInterest = debt * monthlyRate;
    cout << "monthlyInterest = " << monthlyInterest << ",  ";

    monthlyInterestSum += monthlyInterest;
    
    // WHEN THE AMOUNT OF MONEY NEEDED TO PAYOFF IS LESS THAN 
    // THE NORMAL MONTHLY PAYMENT AMOUNT, EXIT THE LOOP.
    if ( ( debt + monthlyInterest ) < monthlyPayment )
    {
      cout << "the last payment = " << ( debt + monthlyInterest )
           << endl;
      break;
    }  

    towardLoan = (monthlyPayment - monthlyInterest);
    cout << "towardLoan = " << towardLoan << ",  ";
  
    debt = debt - towardLoan;
    cout << "debt = " << debt << endl;
  }


  // PRINT OUT THE SUMMARY
  cout << "The number of months needed to payoff the loan: " 
       << month << endl;
  cout << "The amount of interest paid on the loan: " 
       << monthlyInterestSum << endl;
  
  
  return 0;
}


/*
/homes/home30/hkim16/107/lab5> a.out
The total amount of the loan? 1000
The monthly payment? 50
The monthly interest rate? 0.015
Month #1: monthlyInterest = 15.00,  towardLoan = 35.00,  debt = 965.00
Month #2: monthlyInterest = 14.47,  towardLoan = 35.53,  debt = 929.47
Month #3: monthlyInterest = 13.94,  towardLoan = 36.06,  debt = 893.42
Month #4: monthlyInterest = 13.40,  towardLoan = 36.60,  debt = 856.82
Month #5: monthlyInterest = 12.85,  towardLoan = 37.15,  debt = 819.67
Month #6: monthlyInterest = 12.30,  towardLoan = 37.70,  debt = 781.97
Month #7: monthlyInterest = 11.73,  towardLoan = 38.27,  debt = 743.70
Month #8: monthlyInterest = 11.16,  towardLoan = 38.84,  debt = 704.85
Month #9: monthlyInterest = 10.57,  towardLoan = 39.43,  debt = 665.42
Month #10: monthlyInterest = 9.98,  towardLoan = 40.02,  debt = 625.40
Month #11: monthlyInterest = 9.38,  towardLoan = 40.62,  debt = 584.79
Month #12: monthlyInterest = 8.77,  towardLoan = 41.23,  debt = 543.56
Month #13: monthlyInterest = 8.15,  towardLoan = 41.85,  debt = 501.71
Month #14: monthlyInterest = 7.53,  towardLoan = 42.47,  debt = 459.24
Month #15: monthlyInterest = 6.89,  towardLoan = 43.11,  debt = 416.13
Month #16: monthlyInterest = 6.24,  towardLoan = 43.76,  debt = 372.37
Month #17: monthlyInterest = 5.59,  towardLoan = 44.41,  debt = 327.95
Month #18: monthlyInterest = 4.92,  towardLoan = 45.08,  debt = 282.87
Month #19: monthlyInterest = 4.24,  towardLoan = 45.76,  debt = 237.11
Month #20: monthlyInterest = 3.56,  towardLoan = 46.44,  debt = 190.67
Month #21: monthlyInterest = 2.86,  towardLoan = 47.14,  debt = 143.53
Month #22: monthlyInterest = 2.15,  towardLoan = 47.85,  debt = 95.68
Month #23: monthlyInterest = 1.44,  towardLoan = 48.56,  debt = 47.12
Month #24: monthlyInterest = 0.71,  the last payment = 47.83
The number of months needed to payoff the loan: 24
The amount of interest paid on the loan: 197.83
/homes/home30/hkim16/107/lab5>
*/