PA 2 Credit Card Interest

//Christian Ballard
//COSC 1336-001
//Calculates the interest on a persons credit card.
//January 15, 15

#include <iostream>
#include <iomanip>
using namespace std;

//Prototypes
double averageDailyBalanceFunction(double, double, int, int); // Calculates the users average daily balance.
double interestFunction(double, double); // The interest that is added after every cycle.
void displayFunction(double, double, int, int, double, double, double); // Displays all of the inputs and calculated data.


int main()
{

    double averageDailyBalance = 0.0; // Calculates the users average daily balance.
    double netBalance = 0.0; // Users current account balance.
    double payment = 0.0; // Payment amount this cycle.
    int d1 = 0; // Number of days in the billing cycle.
    int d2 = 0; // Number of days payment is made before billing cycle.
    double interest = 0.0; // Interest that is added this cycle.
    double monInterestRate = 0.0; // The monthly interest rate.

    for (int counter = 0; counter < 3; counter++)
    {
        cout << "Please enter your current balance. " << endl << "$";
        cin >> netBalance;

        cout << "Please enter your desired payment. " << endl << "$";
        cin >> payment;

        cout << "Please enter the number of days in the billing cycle. " << endl;
        cin >> d1;

        cout << "Please enter the number of days payment is made before the billing cycle. " << endl;
        cin >> d2;

        cout << "What is the monthly interest rate? (ex. 1.62) " << endl;
        cin >> monInterestRate;
        monInterestRate = monInterestRate / 100;

        averageDailyBalance = averageDailyBalanceFunction(netBalance, payment, d1, d2);

        // Sets the variable 'interest' to the return value from 'interestFunction'.
        interest = interestFunction(averageDailyBalance, monInterestRate);

        displayFunction(netBalance, payment, d1, d2, monInterestRate, averageDailyBalance, interest);
    }


    system("pause");
    return 0;
}

// Calculates the users average daily balance.
double averageDailyBalanceFunction(double netBalance, double payment, int d1, int d2)
{
    double averageDailyBalance; // Calculates the users average daily balance.
    averageDailyBalance = (netBalance * d1 - payment * d2) / d1;
        return averageDailyBalance;
}

// The interest that is added this cycle.
double interestFunction(double averageDailyBalance, double monInterestRate)
{

    return (averageDailyBalance * monInterestRate);
}

// Displays all of the inputs and calculated data.
void displayFunction(double netBalance, double payment, int d1, int d2, double monInterestRate,
                     double averageDailyBalance, double interest)
{
    cout << fixed << setprecision(2); // Sets the decimal place to spots behind the zero.
    cout << "Your new current balance is $" << netBalance << endl << endl;
    cout << "Your last payment was $" << payment << endl << endl;
    cout << "The days in your billing cycle are " << d1 << endl << endl;
    cout << "The number of days you paid before the billing date was " << d2 << endl << endl;
    cout << "Your average daily balance is $" << averageDailyBalance << endl << endl;
    cout << "Your current interest is $" << interest << endl << endl;

}