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