How to use multiple instances of a class containing QTimer?

[nhungr]

Thanks for the useful hints! The problem did indeed come from the fact that I didn't have an events loop running... which means my qtimer::connect events didn't get processed. So I need to make a call to QCoreApplication::exec(), as shown here for example. Although it works now, it's made me run into another conceptual problem: is there any way of interrupting the qtimers prematurely (by pressing a key on the keyboard for example) since the application now requires the exec routine to terminate before moving on?

[amleto]

yes, there is a way to stop a timer
http://doc.qt.io/qt-4.8/QTimer#stop

[yeye_olive]

Now that your application has an event loop, you indeed need to call QCoreApplication::exit() or QCoreApplication::quit() for the program to exit. If I understand correctly, currently your application runs in a console, sets up some timers, some functions are called when they time out, and at some point QCoreApplication::quit() is called. Now you would also like your application to exit immediately when a certain key is pressed without waiting for the above scenario to complete. Is that correct?

If it is the case, then you do not need to stop the timers. What you need is a way to handle some event (key press, or termination request from the OS) and make sure that QCoreApplication::quit() gets called. This is not trivial (and unfortunately platform-specific), but it may not be necessary. In its current state, your program is immediately killed if you hit Ctrl+C as it (currently) ignores the termination request. Of course this ends the program brutally but it is OK if no cleanup is required. It is definitely something to avoid if e.g. your program may be in the middle of writing to some files. So the main question is: is it acceptable if your program gets killed without having the chance to run some cleanup code?

[nhungr]

Yes, that's exactly what I need. However, instead of exiting the application entirely, I want it just to exit the events loop and then continue with the rest of the code in my main loop. In other words. is there a way of polling inside the Qtimer slot whether a key has been pressed and stopping the timer in consequence? Once the last timer has been stopped, quit the events loop and go on with the rest of the code?
Perhaps my approach of using qtimers is not a good approach? Is it worthwhile looking into using QThreads instead?
Thanks very much.

[amleto]

to deal with key press events you would normally have a gui and be using widgets. Otherwise you are either dealing with non-standard c++ headers or doing things like peek or cin.get.


I don't know if QCoreApplication::winEventFilter could help you whilst not using any gui to handle key presses

[wysota]

Usually it's possible to monitor stdin using QSocketNotifier but it requires to disable buffering for stdin.