How works QApplication::exit()

On my application I try to retrieve data from a database. If this step is succesfull the application continues, Instead I want that the application shows a QMessage::critical(...) and closes with QApplication::exit(). The error appears but the application dosn't stops. The code is:

Code:

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wMain::wMain(QWidget *parent) : QWidget(parent), ui(new Ui::wMain)
{
    ui->setupUi(this);
    this->actualizarInterfaz();
}
 
void wMain::actualizarInterfaz()
{
        DAO* aDao = new DAO("");
        this->asg = aDao->Query(1);
        delete aDao;
 
        if(this->asg != NULL)
        {
            // populate gui with data recovered
        }
        else
        {
            QMessageBox::critical(
                    this,
                    "Error",
                    "...");
            qApp->exit(1);
        }
}

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How could I fix this? There are another ways to do it?

What exactly do you mean that the application "doesn't stop"? Did you read about differences between QCoreApplication::exit() and ::exit()?

I agree with wysota. In this case, I'm just figure how qApp->exit() called. I guess that your problem is calling QApplication::exit() before entering the application main loop. In the other word, QApplication::exit() called before QApplication::exec() executed. So if you want to stop your application before QApplication entering the main loop, call ::exit() that provided by stdlib.h.

I discovered another way to quit your Qt app before the main event loop has started a couple of days ago. I needed to quit the application within the constructor of the main window, and it seems that the following does the job:

Code:

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QMetaObject::invokeMethod(this, "close", Qt::QueuedConnection);

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X-T

Quote:

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I discovered another way to quit your Qt app before the main event loop has started.

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That's not TRUE, in fact the application event loop has started and the Widget costructed, show, then closed by method invocation. You are misunderstand with Qt:QueuedConnection. Do you actually know what you've done?

If you want to quit the application then just return from main.