//* A sample program that uses a menu *
#include <iostream>
using namespace std;

void task_A() {
    // ... anything that would be useful for you
    // ... to do in your program when user selects 
    // ... this particular task
    cout << "Task A has been performed" << endl;
}

void task_B(double par) {
    // ... anything that would be useful for you
    // ... to do in your program when user selects 
    // ... this particular task
    cout << "Task B has been performed for parameter " 
         << par << endl;
}

double task_C(double p1, int p2) {
    // ... anything that would be useful for you
    // ... to do in your program when user selects 
    // ... this particular task
    double result=p1*p2;
    cout << "Task C has been performed for parameters " 
         << p1 << " and " << p2 << endl;
    return(result);
}



int main() {

    char choice;
    // we need to declare the choice outside of this do-while loop
    // because we need to check it in the exit condition

    do {

        // print or repeat the main menu, ask for the selection
        cout << "\n\nMAIN MENU:\n\n"
             << "a - do task A\n" 
             << "b - do task B\n" 
             << "c - do task C\n" 
             << "X - eXit the program\n" 
             << "\n--> ";
        cin >> choice;

        // you cannot declare variables directly in switch-case
        // so we declare them before it. There are ways around though
        double x, y, r;
        int z;

        switch (choice) {
        case 'a' :
        case 'A' :
            task_A();
            break;
        case 'b' :
        case 'B' :
            cout << "Please enter a number " << endl;
            cin >> x;
            task_B(x);
            break;
        case 'c' :
        case 'C' :
            cout << "Please enter two numbers " << endl;
            cin >> y >> z;
            r=task_C(y, z);
            cout << "The answer is " << r << endl;
            break;
        case 'X' :
            // do nothing here, we will exit the main loop soon
            break;
        default  : 
            cout << "\aI am sorry, but I did not recognize your selection\n"
<< "Could you please choose one from the following options:\n\n" << endl;
        }

    } while (choice!='X');

    cout << "Thank you for using this software.\n"
         << "I hope to see you again soon." << endl;

    return(0);
}