Qt Application hangs on exit (after QDialog exec)

I'm using Qt to build a UI and I need to have a dialog window show up before the main app window, so that the user can select some files to load ans things like that. What I've got is a fairly simple main:

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    IView *view = new QtView();
    view->showView();
    int rc = a.exec();
    std::cout << "exit" << std::endl;
    return rc;
}

the QtView class is the concrete implementation of the IView interface. It has the mainwindow instance and a QDialog instance too. int the view->showView() method this is what I'开发者_JS百科ve got:

void QtView::showView()
{
    this->_configDialog->exec();
    this->_mainAppWindow->show();
}

It works fine, the dialog opens and when the user clicks OK, exec returns and the main window appears. The problem is that when I quit the main window I get a zombie process and the app just seems to hang even though all the windows have been closes and I never get the "exit" I print out in the main just before the main returns. I'm not sure what I'm doing wrong, but I get the same resutl even if I click on the cross to close the dialog, the main window opens up, and once closed the whole things just hangs there.

If anyone has any advice, that would be cool. Thanks.

I Fixed my problem. I used the accepted/rejected/finished(int) signal from the QDialog to trigger the show slot on the main app window, and display it if the dialog was accepted. Thanks for the help anyway.

I think the possible reason for this behavior is that your configuration dialog may not have a parent widget set on it (it's a blind guess though as you haven't cited the relevant portion of the code). That's because QApplication by default would only quit when all the windows with no parent are closed. And the thing is, a dialog is not a window, technically - it has the Qt::Dialog window type rather than Qt::Window. That means any "orphaned" dialog, that is closed, will still prevent the application from exiting automatically.

The solution? Either giving a parent to the dialog or enabling the Qt::WA_QuitOnClose attribute:

this->_configDialog->setAttribute(Qt::WA_QuitOnClose);