Calculator v2.cpp

#include <iostream>

using namespace std;

void read2Numbers(double &dNum1, double &dNum2);
int menu();
bool sum(double dNum1, double dNum2, double &dResult);
bool sub(double dNum1, double dNum2, double &dResult);
bool multi(double dNum1, double dNum2, double &dResult);
bool divide(double dNum1, double dNum2, double &dResult);
void runCal();

int main(void)
{
    cout << "\t\t\t\tWelcome to The Calculator :D \n\n";
    runCal();
    return 0;
}

void read2Numbers(double &dNum1, double &dNum2)
{

        dNum1 = dNum2 = 0;
        cout << "Please Enter 2 Numbers: \n";
        cin >> dNum1 >> dNum2;
        if (cin.fail())
        {
            cout << "Retry: \n";
            cin.clear();
            cin.ignore(10000, '\n');
            read2Numbers(dNum1, dNum2);
        }
        return;
}

int menu()
{
    int iChoice = 0;
    cout << "Please Enter Your Choice: \n1: Sum, 2: Subtraction, 3: Multiply, 4:Divide, 5:Input 2 Numbers Again: \n";
    cin >> iChoice;
    if (cin.fail())
    {
        cout << "Retry: \n";
        cin.clear();
        cin.ignore(10000, '\n');
        return menu();
    }
    return iChoice;
}

bool sum(double dNum1, double dNum2, double &dResult)
{
    dResult = dNum1 + dNum2;
    return true;
}

bool sub(double dNum1, double dNum2, double &dResult)
{
    dResult = dNum1 - dNum2;
    return true;
}

bool multi(double dNum1, double dNum2, double &dResult)
{
    dResult = dNum1 * dNum2;
    return true;
}

bool divide(double dNum1, double dNum2, double &dResult)
{
    if (dNum2 == 0)
    {
        cout << "Cannot Divide by Zero!\nRetry: ";
        return false;
    }
    dResult = dNum1 / dNum2;
    return true;
}

void runCal()
{
    double dNum1 = 0, dNum2 = 0, dResult = 0;
    int iChoice = 0;
    bool bFinished = false;
    while (!bFinished)
    {
        read2Numbers(dNum1, dNum2);
        iChoice = menu();
        if (iChoice == 5)
            continue;
        else if (iChoice == 1)
            bFinished = sum(dNum1, dNum2, dResult);
        else if (iChoice == 2)
            bFinished = sub(dNum1, dNum2, dResult);
        else if (iChoice == 3)
            bFinished = multi(dNum1, dNum2, dResult);
        else if (iChoice == 4)
            bFinished = divide(dNum1, dNum2, dResult);
    }
    cout << "Result = " << dResult << endl;
}