#include<qapplication.h>#include<qwidget.h>#include<qpushbutton.h>#include<qfont.h>#include<qlcdnumber.h>#include<qslider.h>class MyMainWindow:public QWidget{    public:    MyMainWindow();    private:    QPushButton *b1;    QLCDNumber *lcd;    QSlider *slider;};MyMainWindow::MyMainWindow(){setGeometry(100,100,300,200);b1=new QPushButton("Quit",this);b1->setGeometry(10,10,80,40);b1->setFont(QFont("Times",18,QFont::Bold));lcd=new QLCDNumber(2,this);lcd->setGeometry(100,10,190,180);slider=new QSlider(Vertical,this);slider->setGeometry(10,60,80,130);connect(b1,SIGNAL(clicked()),qApp,SLOT(quit()));connect(slider,SIGNAL(valueChanged(int),		      lcd,SLOT(display(int)));    }int main(int argc,char **argv){QApplication a(argc,argv);MyMainWindow w;a.setMainWidget(&w);w.show();a.exec();}