带有QT的多个窗口

Question

I'm a student and for my thesis I want to create a question-based game; I would like to use QT to elaborate the graphical interface, but I've never used it and I don't know how to create an application with multiple windows. There is a base-class (abstract) called "Form" and three others classes that inherits from Form: MainMenuForm, LoginForm and GameForm.

In some of the examples I found, the layout of the window is setted in the constructor and in the main is called the method show(), but I would like to do something like this in the main:

// Creates a FormFactory object and ensures singleton instance
FormFactory * factory;

factory = factorySingleton.GetFactory();

//select a Form to display

int choice = 1;
Form * actualForm;

while (choice != 0)
{
    factory->Init(choice);
    actualForm = factory->ReturnActualForm();
    choice = actualForm->Display();
}

The Display method, common to every derived-Form, must return an int that indicates which window display (for example, the Display method of MainMenuForm returns 2 if the user want to proceed to the Login window or 0 if the user want to close the application); obviously, the Display method must also show the form.

Finally, I noticed that in all examples they write

return app.exec();

in the end of the main.

For my project, where am I supposed to write app.exec()? Before, after or inside the while statement?

Answer 1

Your design is quite bad. The code you quoted should be in a separate class which is instantiated before calling app.exec(). The current solution only allows to select the form once, it will be displayed and when you close it, the program ends.

Read Qt docs about signals and slot, and how to write Qt GUI apps, you need a different approach.