How to quit a QApplication through class private slot

[exSnake]

I'll go fast to the point, i have followed this italian tutorial, but seem to be so broken, he said to me to create a quit slot for the notepad for let the user choice if they really want to close it or not, but how i can say that the Quit() slot have to close the QApplication created in the main??? I've tried to implement it to use "this->quit()" but whenever i press it reopen again.
this is the code:

Main.cpp

#include <QApplication>
#include "notepad.h"


int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Notepad w;
    w.show();


    return a.exec();
}

Notepad.h

#ifndef NOTEPAD_H
#define NOTEPAD_H
#include <QApplication>
#include <QtWidgets>
#include <QWidget>


class Notepad : public QWidget
{
    Q_OBJECT

public:
    explicit Notepad(QWidget *parent = 0);
    ~Notepad();

private slots:
    void quit();

private:
    QTextEdit *textEdit;
    QPushButton *btnQuit;
};


#endif // NOTEPAD_H

Notepad.cpp

#include "notepad.h"

Notepad::Notepad(QWidget *parent) : QWidget(parent)
{
    textEdit = new QTextEdit;
    btnQuit = new QPushButton(tr("esci"));

    connect(btnQuit,SIGNAL(clicked(bool)),this,SLOT(quit()));

    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(textEdit);
    layout->addWidget(btnQuit);
    setLayout(layout);
    setWindowTitle(tr("Notepad"));
}

Notepad::~Notepad()
{

}

void Notepad::quit(){
    QMessageBox *message = new QMessageBox();
    message->setText("Are you sure?");
    message->setStandardButtons(QMessageBox::Yes | QMessageBox::No);
    int ret = message->exec();
    switch(ret){
        case QMessageBox::Yes:
            quit();
            break;
        case QMessageBox::No:
            break;
    default:
        break;
    }
}

[hskoglund]

Hi, when you're calling quit(); you're just calling your own slot function again (i.e. same as clicking the "Esci" button) try change to:

    case QMessageBox::Yes:
        qApp->quit();
        break;

[exSnake]

So qApp is a pointer to the QApplication "instance" ? Is it right?

I can use it in every class constructor for refer to the QApplication object?

[hskoglund]

Yes and yes :-)