Need help in calculating interest rate on loan

[fatimahtaher]

Hi,

I am new to C# programming and my first assignment requires me to calculate total interest paid on a loan. The user will input the loan, the interest rate per month, and the monthly payment. It has to use a while loop and calculate the following:

Total amount of interest paid and the number of months to pay off the loan.

I am not a finance major so I have some difficulty with the logistics of how to go about doing this. My code so far is really messy and does not work. Please help!

static void Main(string[] args)
      {
         //declare variables
         double amount_borrowed;
         double interest_rate;
         double monthly_payment;
         double leftover_balance;
         double monthly_interest_payment;
         double adjusted_principle;
         double balance;
         double total_interest_paid;
         double total_months;
         int monthCounter;

         
         
         //initialize variables
         amount_borrowed = 0;
         interest_rate = 0;
         monthly_payment = 0;
         adjusted_principle = 0;
         monthly_interest_payment = 0;
         monthCounter = 0;
         total_months = 0;
         leftover_balance = 0;
         total_interest_paid = 0;
         balance = 0;
         adjusted_principle = amount_borrowed - monthly_interest_payment;
         monthly_interest_payment = adjusted_principle * interest_rate;
         leftover_balance = monthly_payment - monthly_interest_payment;
         monthly_interest_payment = (amount_borrowed * interest_rate);
         balance = adjusted_principle - leftover_balance;
         total_interest_paid = monthly_interest_payment;
         
        

         //prompt for input
         Console.WriteLine("Enter amount borrowed: ");
         amount_borrowed = Convert.ToDouble(Console.ReadLine());

         Console.WriteLine("Enter monthly interest rate: ");
         interest_rate = Convert.ToDouble(Console.ReadLine());

         Console.WriteLine("Enter monthly payment: ");
         monthly_payment = Convert.ToDouble(Console.ReadLine());
                           
         //loop until balance is 0
         while (balance > 0)
         {
            //Count the number of months
            monthCounter++;

            //Calculate the balance
            balance = adjusted_principle - leftover_balance;

            // Calculate the total interest paid
            total_interest_paid = monthly_interest_payment * total_months;

            Console.WriteLine("Your new balance: " +  balance);
            balance = Convert.ToDouble(Console.ReadLine());
            
         }//end while

         

         Console.WriteLine("You paid " + total_interest_paid + " in interest");
         total_interest_paid = Convert.ToDouble(Console.ReadLine());

         Console.WriteLine("It took " + total_months + " months to pay off your loan");
         total_months = Convert.ToDouble(Console.ReadLine());


      }
   }
}

[horace1]

I have done some modifications and got it to the point where it will compile.

this reads the data in and does some (faulty) calculations - code at the end of the program is commented out - fix that when the rest is working

#include <iostream>
using namespace std;

int main()
      {
         //declare variables
         double amount_borrowed;
         double interest_rate;
         double monthly_payment;
         double leftover_balance;
         double monthly_interest_payment;
         double adjusted_principle;
         double balance;
         double total_interest_paid;
         double total_months;
         int monthCounter;

         
         
         //initialize variables
         amount_borrowed = 0;
         interest_rate = 0;
         monthly_payment = 0;
         adjusted_principle = 0;
         monthly_interest_payment = 0;
         monthCounter = 0;
         total_months = 0;
         leftover_balance = 0;
         total_interest_paid = 0;
         balance = 0;       

         //prompt for input
         cout << "Enter amount borrowed: ";
         cin >> amount_borrowed;

         cout <<"Enter monthly interest rate: ";
         cin >> interest_rate;

         cout <<("Enter monthly payment: ");
         cin>>monthly_payment ;
         monthly_interest_payment = adjusted_principle * interest_rate;
         adjusted_principle = amount_borrowed - monthly_interest_payment;
         leftover_balance = monthly_payment - monthly_interest_payment;
         monthly_interest_payment = (amount_borrowed * interest_rate);
         balance = adjusted_principle - leftover_balance;
         total_interest_paid = monthly_interest_payment;
                           
         //loop until balance is 0
         while (balance > 0)
         {
            //Count the number of months
            monthCounter++;

            //Calculate the balance
            balance = adjusted_principle - leftover_balance;

            // Calculate the total interest paid
            total_interest_paid = monthly_interest_payment * total_months;

            cout <<"Your new balance: "<<  balance << endl;
            //balance = Convert.ToDouble(Console.ReadLine());
            
         }//end while

       
        // Console.WriteLine("You paid " + total_interest_paid + " in interest");
        // total_interest_paid = Convert.ToDouble(Console.ReadLine());

       //  Console.WriteLine("It took " + total_months + " months to pay off your loan");
       // total_months = Convert.ToDouble(Console.ReadLine());
   }

you need to look at the code for the interest calculations

[fatimahtaher]

I have done some modifications and got it to the point where it will compile.

this reads the data in and does some (faulty) calculations - code at the end of the program is commented out - fix that when the rest is working

#include <iostream>
using namespace std;

int main()
      {
         //declare variables
         double amount_borrowed;
         double interest_rate;
         double monthly_payment;
         double leftover_balance;
         double monthly_interest_payment;
         double adjusted_principle;
         double balance;
         double total_interest_paid;
         double total_months;
         int monthCounter;

         
         
         //initialize variables
         amount_borrowed = 0;
         interest_rate = 0;
         monthly_payment = 0;
         adjusted_principle = 0;
         monthly_interest_payment = 0;
         monthCounter = 0;
         total_months = 0;
         leftover_balance = 0;
         total_interest_paid = 0;
         balance = 0;       

         //prompt for input
         cout << "Enter amount borrowed: ";
         cin >> amount_borrowed;

         cout <<"Enter monthly interest rate: ";
         cin >> interest_rate;

         cout <<("Enter monthly payment: ");
         cin>>monthly_payment ;
         monthly_interest_payment = adjusted_principle * interest_rate;
         adjusted_principle = amount_borrowed - monthly_interest_payment;
         leftover_balance = monthly_payment - monthly_interest_payment;
         monthly_interest_payment = (amount_borrowed * interest_rate);
         balance = adjusted_principle - leftover_balance;
         total_interest_paid = monthly_interest_payment;
                           
         //loop until balance is 0
         while (balance > 0)
         {
            //Count the number of months
            monthCounter++;

            //Calculate the balance
            balance = adjusted_principle - leftover_balance;

            // Calculate the total interest paid
            total_interest_paid = monthly_interest_payment * total_months;

            cout <<"Your new balance: "<<  balance << endl;
            //balance = Convert.ToDouble(Console.ReadLine());
            
         }//end while

       
        // Console.WriteLine("You paid " + total_interest_paid + " in interest");
        // total_interest_paid = Convert.ToDouble(Console.ReadLine());

       //  Console.WriteLine("It took " + total_months + " months to pay off your loan");
       // total_months = Convert.ToDouble(Console.ReadLine());
   }

you need to look at the code for the interest calculations

Thank you. I will try this.

Fatimah