Qt qApp

qApp

A global pointer referring to the unique application object. It is equivalent to the pointer returned by the QCoreApplication::instance() function except that, in GUI applications, it is a pointer to a QApplication instance.





Only one application object can be created.

See also QCoreApplication::instance().

#ifndef MYWIDGET_H

#define MYWIDGET_H

#include <QtWidgets/QDialog>

#include "ui_mywidget.h"

class mywidget : public QDialog

{

	Q_OBJECT

public:

	mywidget(QWidget *parent = 0);

	~mywidget();

private:

	Ui::mywidgetClass ui;

};

#endif // MYWIDGET_H

#include "mywidget.h"

#include <QtWidgets/QPushButton>

#include <QtWidgets/QApplication>

#include <QFont>

mywidget::mywidget(QWidget *parent)

	: QDialog(parent)

{

	ui.setupUi(this);

	setMinimumSize(200, 120);

	setMaximumSize(200, 120);

	QPushButton *quit = new QPushButton("Quit", this);

	quit->setGeometry(62, 40, 75, 30);

	quit->setFont(QFont("Times", 18, QFont::Bold));

	connect(quit, SIGNAL(clicked()), qApp, SLOT(quit()));

}

mywidget::~mywidget()

{

}

所以就可以实现单击“Quit”退出