How to make my program run until it is 0 for the payment?

Question

I am trying to calculate that after x month the balance would be $0. For some reason, it is only looping once and stopped. I have tried it out with other formulas and loop but it is not working.

The question is: Interest on a loan is paid on a declining balance, and hence a loan with an interest rate of, say, 14 percent can cost significantly less than 14 percent of the balance. Write a program that takes a loan amount and interest rate as input and then outputs the monthly payments and balances of the loan until the loan is paid off. Assume that the monthly payments are one-twentieth of the original loan amount and that any amount in excess of the interest is credited toward decreasing the balance due. Thus, on a loan of $20,000, the payments would be $1,000 a month. If the interest rate is 10 percent, then each month the interest is one-twelfth of 10 percent of the remaining balance. The first month (10 percent of $20,000)/12, or $166.67, would be paid in interest, and the remaining $833.33 would decrease the balance to $19,166.67. The following month the interest would be (10 percent of $19,166.67)/12, and so forth. Also, have the program output the total interest paid over the life of the loan. Finally, determine what simple annualized percentage of the original loan balance was paid in interest. For example, if $1,000 was paid in interest on a $10,000 loan and it took 2 years to pay off, then the annualized interest is $500, which is 5 percent of the $10,000 loan amount.

Thanks for all the help in advance. This is what I have so far:

#include <iostream>

using namespace std;

int main()
{

    double interestRate , loanAmount , principalPaid, monthlyPayment;

    int month = 1;

    const double MONTHLY_PAYMENT_RATE = 1/20; 

    cout << "Please enter your loan amount:  \n";
    cin >> loanAmount;
    cout << "Please enter the interest rate:  \n";
    cin >> interestRate;
    cout << "Please enter the monthly payment: \n";
    cin >> monthlyPayment;

    cout << "For the 1 month your balance is $" << loanAmount << endl;

    while (interestRate >0 )
    {
        month++;
        interestRate = 10/12*loanAmount;
        principalPaid = monthlyPayment - interestRate;
                loanAmount -=principalPaid;
    }
        cout << "After " << month << " month , your balance is : $" << loanAmount << endl;

    return 0;

}

Im assuming that month should be in the while loop and it being out makes it apply ++ only one time which makes you think that the program runs one time when in fact it doesnt — Abdelrhman Hosny, Sep 18 '20 at 05:48
Also, your `interestRate` variable gets an input value as an interest rate, but in the loop it is used as interest paid and you hard-code the interest rate to 10/12 (=0%). — Ken Y-N, Sep 18 '20 at 05:50

score 3 · Answer 1 · answered Sep 18 '20 at 05:51

3

Your 10/12 is an integer division returning 0. You need to use double division 10.0/12.

answered Sep 18 '20 at 05:51

Thomas

1,225
7
16

1

...and note MONTHLY_PAYMENT_RATE too, although the constant is not used. – Bathsheba Sep 18 '20 at 06:00
1

Or just `10*loanAmount/12` – Alan Birtles Sep 18 '20 at 06:09
@AlanBirtles: To my mind that's more vulnerable to refactoring. I always promote the first coefficient. – Bathsheba Sep 18 '20 at 06:10
I am not planning to use MONTHLY_PAYMENT_RATE but my I was told to use that as a constant that's why – Skylar Yang Sep 18 '20 at 06:13
@SkylarYang: You might to eventually. Your formula `principalPaid = monthlyPayment - interestRate;` looks funny. Didn't you want `interestPaid`? – Bathsheba Sep 18 '20 at 06:20

How to make my program run until it is 0 for the payment?

1 Answers1