This is simple example How to exit after QCoreApplication::exec()
Run app and after 3 second QCoreApplication_quit_example will close automatically with message "good bye".
To exit from you infinite cycle QCoreApplication::exec() try this
QTimer::singleShot(1000, this, &rial::closeApp); //if you need process some code in closeApp()
or this
QTimer::singleShot(1000, QCoreApplication::instance(), SLOT(quit())); //if you need quit() only
Also you can use Ctrl+C to exit. If user send Ctrl+C signal QCoreApplication_quit_example will use non-Qt function SigInt_Handler(). It tested on Ubuntu.
QCoreApplication_quit_SIGINT_example is more powerfull then QCoreApplication_quit_example. If user send Ctrl+C signal QCoreApplication_quit_SIGINT_example will use Qt non-static method rial::handleSignal(). In this method Qt start QTimer for 3 seconds and after do closeApp(). If user don't press Ctrl+C in console for QCoreApplication_quit_SIGINT_example this app will wating forever.
You can run this apps using Qt Creator. You can use external terminal if you need use this way
Run proj in external terminal
You can send SIGINT by Ctr+C key. But also you can send SIGINT using Debug mode via GDB console. Before sending "signal 2" don't forget make Pause!
SIGINT by GDB in Qt Creator