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Sourcecode: qt4-x11 version File versions  Download package

int QApplication::exec (  ) [static, inherited]

Enters the main event loop and waits until exit() is called, then returns the value that was set to exit() (which is 0 if exit() is called via quit()).

It is necessary to call this function to start event handling. The main event loop receives events from the window system and dispatches these to the application widgets.

Generally, no user interaction can take place before calling exec(). As a special case, modal widgets like QMessageBox can be used before calling exec(), because modal widgets call exec() to start a local event loop.

To make your application perform idle processing, i.e., executing a special function whenever there are no pending events, use a QTimer with 0 timeout. More advanced idle processing schemes can be achieved using processEvents().

We recommend that you connect clean-up code to the {QCoreApplication::}{aboutToQuit()} signal, instead of putting it in your application's {main()} function because on some platforms the QApplication::exec() call may not return. For example, on Windows when the user logs off, the system terminates the process after Qt closes all top-level windows. Hence, there is no guarantee that the application will have time to exit its event loop and execute code at the end of the {main()} function after the QApplication::exec() call.

See also:
quitOnLastWindowClosed, quit(), exit(), processEvents(), QCoreApplication::exec()

Reimplemented from QCoreApplication.

Definition at line 3520 of file qapplication.cpp.

References QAccessible::setRootObject().

{
#ifndef QT_NO_ACCESSIBILITY
    QAccessible::setRootObject(qApp);
#endif
    return QCoreApplication::exec();
}

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