#ifndef MESSAGEBOX_H#define MESSAGEBOX_H#include 
       
        #include "ui_messagebox.h"class MessageBox : public QDialog{	Q_OBJECTpublic:	MessageBox(QWidget *parent = 0, Qt::WFlags flags = 0);	~MessageBox();private:	Ui::MessageBoxClass ui;	QLabel *label;	private slots:		void slotQuestion();		void slotInformation();		void slotWarning();		void slotCritical();		void slotAbout();		void slotAboutQt();		void slotCustom();};#endif // MESSAGEBOX_H
       

#include "messagebox.h"MessageBox::MessageBox(QWidget *parent, Qt::WFlags flags)	: QDialog(parent, flags){	ui.setupUi(this);	setWindowTitle(tr("Message Box Example"));	label = new QLabel;	QPushButton *btn1 = new QPushButton("Question");	QPushButton *btn2 = new QPushButton("Information");	QPushButton *btn3 = new QPushButton("Warning");	QPushButton *btn4 = new QPushButton("Critical");	QPushButton *btn5 = new QPushButton("About");	QPushButton *btn6 = new QPushButton("About Qt");	QPushButton *btn7 = new QPushButton("Custom");	QGridLayout *grid = new QGridLayout;	grid->addWidget(btn1,0,0);	grid->addWidget(btn2,0,1);	grid->addWidget(btn3,1,0);	grid->addWidget(btn4,1,1);	grid->addWidget(btn5,2,0);	grid->addWidget(btn6,2,1);	grid->addWidget(btn7,3,0);	QVBoxLayout *mainLayout = new QVBoxLayout;	mainLayout->setMargin(10);	mainLayout->setSpacing(20);	mainLayout->addWidget(label);	mainLayout->addLayout(grid);	setLayout(mainLayout);	connect(btn1,SIGNAL(clicked()),this,SLOT(slotQuestion()));	connect(btn2,SIGNAL(clicked()),this,SLOT(slotInformation()));	connect(btn3,SIGNAL(clicked()),this,SLOT(slotWarning()));	connect(btn4,SIGNAL(clicked()),this,SLOT(slotCritical()));	connect(btn5,SIGNAL(clicked()),this,SLOT(slotAbout()));	connect(btn6,SIGNAL(clicked()),this,SLOT(slotAboutQt()));	connect(btn7,SIGNAL(clicked()),this,SLOT(slotCustom()));}MessageBox::~MessageBox(){}void MessageBox::slotQuestion(){	switch(QMessageBox::question(this,"Question",tr("It's end of document,search from begin?"),		QMessageBox::Ok|QMessageBox::Cancel,QMessageBox::Ok))	{	case QMessageBox::Ok:		label->setText(" Question button / Ok ");		break;	case QMessageBox::Cancel:		label->setText(" Question button / Cancel ");		break;	default:		break;	}	return;}void MessageBox::slotInformation(){	QMessageBox::information(this,"Information",tr("anything you want tell user"));	return;}void MessageBox::slotWarning(){	switch(QMessageBox::warning(this,"Warning",tr("Save changes to document?"),		QMessageBox::Save|QMessageBox::Discard|QMessageBox::Cancel,QMessageBox::Save))	{	case QMessageBox::Save:		label->setText(" Warning button / Save ");		break;	case QMessageBox::Discard:		label->setText(" Warning button / Discard ");		break;	case QMessageBox::Cancel:		label->setText(" Warning button / Cancel ");		break;	default:		break;	}	return;}void MessageBox::slotCritical(){	QMessageBox::critical(this,"Critical",tr("tell user a critical error"));	label->setText(" Critical MessageBox ");	return;}void MessageBox::slotAbout(){	QMessageBox::about(this,"About",tr("Message box example!"));	label->setText(" About MessageBox ");	return;}void MessageBox::slotAboutQt(){	QMessageBox::aboutQt(this,"About Qt");	label->setText(" About Qt MessageBox ");	return;}void MessageBox::slotCustom(){	QMessageBox customMsgBox;	customMsgBox.setWindowTitle("Custom message box");	QPushButton *lockButton = customMsgBox.addButton(tr("Lock"),QMessageBox::ActionRole);	QPushButton *unlockButton = customMsgBox.addButton(tr("Unlock"),QMessageBox::ActionRole);	QPushButton *cancelButton = customMsgBox.addButton(QMessageBox::Cancel);	customMsgBox.setIconPixmap(QPixmap(":/images/linuxredhat.png"));	customMsgBox.setText(tr("This is a custom message box"));	customMsgBox.exec();	if(customMsgBox.clickedButton() == lockButton)		label->setText(" Custom MessageBox / Lock ");	if(customMsgBox.clickedButton() == unlockButton)		label->setText(" Custom MessageBox / Unlock ");	if(customMsgBox.clickedButton() == cancelButton)		label->setText(" Custom MessageBox / Cancel ");	return;}

#include "messagebox.h"#include 
       
        int main(int argc, char *argv[]){	QApplication a(argc, argv);	MessageBox *w=new MessageBox;	w->show();	return a.exec();}