Car Loan Calculation (C++) - c++

Question

My objective is to calculate and output a loan repayment schedule. The thing I would like to get help on is putting the principles added to the equation and printing out the repayment schedule. I am not sure if I did the calculations right as I have not had a personal finance class yet, and still get to grasp the concept of loans.
The loan repayment schedule is based on full price of an auto, their interest rate and their payment, assuming no money is put down. All fees and taxes are included in the price and will be financed. I also have to out put the repayment schedule to both the screen and a file - one month per line. . If the user has a credit rate of 800, they get a 3% annual interest rate; 700+ gets 5% interest rate; 600+ get 7% interest rate; and less than 600 get 12% interest rate
The credit scores for 700, 600, and below 600 are left blank because I am just going to copy the 800 credit score part again but change the interest rates.
// This program calculates a loan depending on the pereson's credit score
// how much they can pay per month. It almost outputs the month, principal,
// payment, interest, and the money that's been applied
#include <iostream>
#include <cstdio>
#include <iomanip>
using namespace std;
int main() {
int month = 0, creditScore = 0, whichCar;
double principle, payment = 0.0, interestPaid, applied, interestRate;
cout << fixed << setprecision(2) << showpoint; // Sets total or whatever to 2 decimal points
cout << "---------------------------------------------" << endl; // Displays welcome banner
cout << "| |" << endl;
cout << "| JOLLY GOOD SHOW WE HAVE CARS AYEEE |" << endl;
cout << "| |" << endl;
cout << "---------------------------------------------" << endl;
cout << endl;
cout << "Hey, I see you want a car. You can only purchase one car though." << endl;
cout << endl;
cout << "1. Furawree: $6,969.69" << endl; // Displays menu of autos
cout << "2. Buggee: $420,420.420" << endl;
cout << "3. Sedon: $900" << endl;
cout << "4. Truck: $900,000.90" << endl;
cout << "5. Couppee: $22,222.22" << endl;
cout << endl;
cout << "Which car would you like to purchase?" << endl; // Asks user car type and user inputs car #
cout << "Please enter the number of the car: ";
cin >> whichCar;
cout << endl;
switch(whichCar) { // If user choses a number 1-5, then it asks them how much they can pay each month for the car and their credit score
case 1: // FURAWREE
principle = 6969.69;
break;
case 2: // BUGGEE
principle = 420420.42;
break;
case 3: // SEDON
principle = 900;
break;
case 4: // TRUCK
principle = 900000.90;
break;
case 5: // COUPPEE
principle = 22222.22;
break;
default: // If user doesn't pick a number from 1-5
cout << "Yea uhhmmm we don't have that sorry, go away." << endl;
}
cout << "Please enter how much you can pay each month for this Furawree: ";
cin >> payment;
cout << "Please enter your credit score: ";
cin >> creditScore;
if (creditScore >= 800) {
interestRate = .03 / 12;
do {
interestPaid = principle * interestRate;
applied = payment - interestPaid;
month++;
} while (principle < 0) ;
cout << "Month " << " Principle " << " Payment " << " Interest " << " Applied " << endl;
cout << month << " $" << principle << " $" << payment << " " << interestPaid << " $" << applied << endl;
} else if (creditScore >= 700) {
// Will be copied from the 800 credit score
} else if (creditScore >= 600) {
// Will be copied from the 800 credit score
} else {
// Will be copied from the 800 credit score
}
cout << endl;
cout << endl;
cout << "Your payment: $" << payment << endl;
cout << "Your credit score: " << creditScore << endl;
cout << endl;
cout << endl;
system("pause");
return 0;
}

Answer 1

Mate, you need to fix code under credit - 800.
loop condition is incorrect
cout is after the loop, therefore it will print only once .
principle is not incremented nor decremented . and you are checking if principle is less than 0, however principle is set more than 0. so the loop will execute only once.
you need a fix some thing like this. I have just fine tuned little bit. pls fix the rest
if (creditScore >= 800) {
interestRate = .03 / 12;
cout << "Month " << " Principle " << " Payment " << " Interest " << " Applied " << endl;
cout <<"-------------------------------------------------------" << endl;
do {
interestPaid = principle * interestRate;
applied = payment - interestPaid;
principle = principle - applied;
cout << month << " $" << principle << " $" << payment << " " << interestPaid << " $" << applied << endl;
month++;
} while (principle > 0) ;
} else if (creditScore >= 700) {
Note :-
The above code is not following any object oriented concepts. Its not even functional programming. Introduce classes, methods to reduce headache and it will help to debug.
use \t\t to get spaces instead of spaces.
This code will need a big re-work to make it look professional .