The Exit action

Take Exit action as an example. If users click it from the File menu, a signal named triggered will be emitted. So, let's connect this signal to a slot of our application instance in the MainWindow class's member function, createActions:

     connect(exitAction, SIGNAL(triggered(bool)), QApplication::instance(), SLOT(quit()));

The connect method takes four parameters: the signal sender, the signal, the receiver, and the slot. Once the connection is made, the slot on the receiver will be called as soon as the signal of the sender is emitted. Here, we connect the triggered signal of the Exit action with the quit slot of the application instance to enable the application to exit when we click on the Exit action.

Now, to compile and run, click the Exit item from the File menu. The application will exit as we expect if everything goes well.