Hello,

I have been working for hours trying to get my mortgage calculator program to work. The purpose of the program is to allow user input of the loan amount, interest rate, and term in years, and then display the mortgage payment amount. I also have to list the loan balance and interest paid over the term of the loan. I am fine with the calculation of the mortgage payment amount. The problem is that I am unable to get the loan balance for each payment and the interest paid for each payment to calculate correctly. Also, I'm unsure how to stop when the loan balance is zero. Any assistance with what I am doing wrong in my calculations and how to stop when the loan balance is zero would be greatly appreciated!

``````#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

int main()
{
//local variables
float LOAN_AMOUNT=0; //loan amt
float INT_RATE=0;	 //interest rate
int TERM_YEARS=0;	 //loan term in years
char quit;			 //determines if user wants to quit

do
{
//Variable declarations
float RATE;					 //converts interest rate into decimal format
float monthlyInterestRate;	 //monthly interest rate
int length_in_months = 12;	 //number of months for a given period
int numberOfPayments;		 //total number of payments
float monthlyPaymentAmt;	 //monthly payment amount
int monthly_payments_counter;//counter that keeps track of the payment number
float loanBalance;			 //loan balance
float monthlyIntPymt;		 //monthly interest payment
int divide_list = 0;		 //displays a partial list for the user
char list_more;				 //enables the user to continue viewing a partial list
float monthlyPrincipalPymt;	 //monthly principal payment

//output message asking for loan amt
cout<<"Input the total loan amount:\n";

//input data
cin>>LOAN_AMOUNT;

//output message asking for interest rate
cout<<"Input the annual interest rate:\n";

//input data
cin>>INT_RATE;

//output message asking for term in years of loan
cout<<"Input the length of the loan in years:\n";

//input data
cin>>TERM_YEARS;

//CALCULATIONS
//rate in decimal format
RATE = INT_RATE / 100;

//number of payments
numberOfPayments = TERM_YEARS * length_in_months;

//monthly interest rate
monthlyInterestRate = RATE / length_in_months;

//monthly payments
monthlyPaymentAmt = (LOAN_AMOUNT*
pow(monthlyInterestRate + 1, numberOfPayments)
* monthlyInterestRate)/(pow(monthlyInterestRate + 1,
numberOfPayments) - 1); //pow returns x raised to the power of y

//output results
cout<<fixed<<setprecision(2)//cout writes text to the screen
<<"\n";
cout<<"Your monthly payment for "
<<TERM_YEARS <<" years\n";
cout<<"for an Interest Rate of "
<<INT_RATE <<"%\n";
cout<<"on a Loan Amount of \$"
<<LOAN_AMOUNT <<" is \$"<<monthlyPaymentAmt<<" a month\n";
cout<<"\n";
cout<<"Payment Number\tLoan Balance\tInterest Paid\n";
cout<<"--------------\t------------\t-------------\n";

//List the payment number, loan balance, and interest paid
//for each period
for (monthly_payments_counter=1; monthly_payments_counter<=numberOfPayments; ++monthly_payments_counter)
{

monthlyIntPymt = loanBalance * monthlyInterestRate;
monthlyPrincipalPymt = monthlyPaymentAmt - (loanBalance * INT_RATE);
loanBalance = loanBalance - monthlyPrincipalPymt;

//displays a partial list and allows the user either continue viewing
//the list, enter a new loan, or exit the program
if (divide_list == 12)
{
cout <<"Type 'c' to continue viewing the list, "
<<"'n' to enter a new loan, or 'e' to exit: ";
cin >> list_more;

if ((list_more == 'c') || (list_more == 'C'))
divide_list = 0;
else if ((list_more == 'n') || (list_more == 'N'))
break;
else if ((list_more == 'e') || (list_more == 'E'))
return 0;
}

//displays the results on the screen for each payment number
cout<<monthly_payments_counter<<"\t\t"
<<loanBalance<<"\t"
<<monthlyIntPymt<<"\t\t\n";
++divide_list;
}

//user can continue in a loop or quit
//output
cout<<"\n";
cout<<"Enter C to continue, Q to quit >";

//user input
cin>>quit;
cout<<"\n";

}
while (((quit!= 'q') && (quit!= 'Q')) || ((quit == 'c') && (quit == 'C')));

cout<<"Thanks for using the calculator!\n";

return 0;

}``````
2
Contributors
1
``````monthlyIntPymt = loanBalance * monthlyInterestRate;