grade average program

//Christian Ballard
//COSC 1330 - 003
//This program should calculate students weighted averages.
#include <iostream>
#include <iomanip>
using namespace std;

double averageGrade(double &);
double classAverage(double &, double, double, double);
void getLetterGrade(char &, double);
void displayGradeReport(double, double, double, double, char);



int main()
{
    double labAverage = 0.0;
    double testAverage = 0.0;
    double projectAverage = 0.0;
    double finalAverage = 0.0;
    char letterGrade = ' ';
    char loopQ = ' ';
    letterGrade = toupper(letterGrade);//Keeping the characters entered uppercase.
    cout << fixed << setprecision(2);//Just putting this here so it doesn't get in the way.

    do//Where the loop will start.
    {
        cout << "Please enter your lab grades." << endl;
        averageGrade(labAverage);//Calls the averageGrade function.
        system("cls");
        cout << "Your lab average is " << labAverage << endl << endl;

        cout << "Please enter your test grades." << endl;
        averageGrade(testAverage);//Calling the averageGrade function once again.
        system("cls");
        cout << "Your test average is " << testAverage << endl << endl;

        cout << "Please enter your project grades." << endl;
        averageGrade(projectAverage);//Calling th averageGrade function AGAIN!.
        system("cls");

        finalAverage = classAverage(finalAverage, labAverage, testAverage, projectAverage);//Calling the classAverage function, and also sending some variables.

        getLetterGrade(letterGrade, finalAverage);//Calling this function will give us a letter grade.

        displayGradeReport(labAverage, testAverage, projectAverage, finalAverage, letterGrade);//This function will display everything.

        cout << "Would you like to enter data for a new student? " << endl; //posttest loop
        cin >> loopQ;
        system("cls");
    } while (loopQ == 'y');
    if (loopQ == 'n')
    {
        cout << "Thank you for using this program!" << endl;
    }

    system("pause");
    return 0;
}

double averageGrade(double &gradeAverage)
{
    double grades = 0.0;
    int numGrades = 0;
    double sum = 0.0;
    char loopies = 'Y'; //Kind of like the primeread.

    do
    {
        cin >> grades;
        numGrades++; //Acumulator
        sum = grades + sum;
        cout << "Would you like to enter more grades? (Y/N)";//This is really annoying but the only way I found to do this.
        cin >> loopies;
        loopies = toupper(loopies);

        switch (loopies) { //Switch to determine what to do if they have no more grades.
        case 'N':
            gradeAverage = sum / numGrades;
        }

    } while (loopies == 'Y'); //End of the loops.
    return gradeAverage;
}

double classAverage(double &averageClass, double labAverage, double testAverage, double projectAverage)
{
    double const LAB_WEIGHT = .50;
    double const TEST_WEIGHT = .40;
    double const PROJECT_WEIGHT = .10;

    averageClass = (labAverage * LAB_WEIGHT) + (testAverage * TEST_WEIGHT) + (projectAverage * PROJECT_WEIGHT);


    return averageClass;
}

void getLetterGrade(char &gradeLetter, double finalAverage)
{
    if (finalAverage >= 90.00)
    {
        gradeLetter = 'A';
    }
    else if (finalAverage >= 80.00 && finalAverage < 90.00)
    {
        gradeLetter = 'B';
    }
    else if (finalAverage >= 70.00 && finalAverage < 80.00)
    {
        gradeLetter = 'C';
    }
    else if (finalAverage >= 60.00 && finalAverage < 70.00)
    {
        gradeLetter = 'D';
    }
    else
    {
        gradeLetter = 'F';
    }
}

void displayGradeReport(double averageLab, double averageTest, double averageProject, double averageFinal, char gradeLetter)
{
    cout << "Your lab average is     " << averageLab << endl;
    cout << "Your test average is    " << averageTest << endl;
    cout << "Your project average is " << averageProject << endl << endl;
    cout << "Your overall class average is " << averageFinal << endl;
    cout << "You currently have a " << gradeLetter << " in this class." << endl << endl;
}