C++ - Looping main resetting objects

Question

I have an issue where I am creating a basic text user interface. In order to keep the text interface looping, I call main() until the user chooses to quit by pressing 0.

However, this recreates my LinkedList list, which I would like to keep as a permanent. I understand that it is bad practice to have it as a global variable, so how can I get around this issue?

int main() {

    int choice, newLatitude, newLongitude;
    string newName;

    LinkedList list;

    cout << "[1] Add a city \n";
    cout << "[2] Display list of cities \n";
    cout << "[0] Exit program \n";
    cin >> choice;
    if (choice == 0) {
        return 0;
    }
    else if (choice == 1) {
        cout << "Enter city name: ";
        cin >> newName;
        cout << "Enter latitude: ";
        cin >> newLatitude;
        cout << "Enter longitude: ";
        cin >> newLongitude;
        City newCity(newName, newLatitude, newLongitude);
        list.addNode(newCity);
    } 
    else if (choice == 2) {
        list.display();
    }
    else {
        cout << "Invalid option, please try again \n";
    }

        main();

    return 0;
}

You should not be calling main() from main(). If you have code you want to re-run, you should put it into a loop inside main, or make it a separate function that you keep calling until your calling code is happy with the results. — StarPilot, Nov 25 '14 at 21:29
Never ever call main(). http://stackoverflow.com/a/2128727/487892 — drescherjm, Nov 25 '14 at 21:30

score 1 · Accepted Answer · answered Nov 25 '14 at 21:28

It is probably not a good idea to use recursion to do this task. If you want it to repeat you are probably better off with a while loop. http://msdn.microsoft.com/en-us/library/2aeyhxcd.aspx

While(true) will loop as long as the statement (true) is true. Aka forever. You could also do something like while(choice != 0) though that would require a slight rework of your code.

int main() {

    int choice, newLatitude, newLongitude;
    string newName;

    LinkedList list;

    while(true)
    {
        cout << "[1] Add a city \n";
        cout << "[2] Display list of cities \n";
        cout << "[0] Exit program \n";
        cin >> choice;
        if (choice == 0) {
            return 0;
        }
        else if (choice == 1) {
            cout << "Enter city name: ";
            cin >> newName;
            cout << "Enter latitude: ";
            cin >> newLatitude;
            cout << "Enter longitude: ";
            cin >> newLongitude;
            City newCity(newName, newLatitude, newLongitude);
            list.addNode(newCity);
        } 
        else if (choice == 2) {
            list.display();
        }
        else {
            cout << "Invalid option, please try again \n";
        }
    }
    return 0;
}

C++ - Looping main resetting objects

1 Answers1