test.cpp~

qt QPushButton QLineEdit

#include <qapplication.h>
#include<qwidget.h>
#include<qpushbutton.h>
#include<qfont.h>
#include<qlineedit.h>
#include<qstring.h>

class MyMainWindow:public QWidget
{
    public:
    MyMainWindow();
    private:
    QPushButton *b1;
    QPushButton *b2;
    QPushButton *b3;
    QLineEdit *ledit;
};


MyMainWindow::MyMainWindow()
{
    setGeometry(100,100,300,200);
    
    b1=new QPushButton("Click here to mark the tesxt",this);
    b1->setGeometry(10,10,280,40);
    b1->setFont(QFont("Times",18,QFont::Bold));
   
    b2=new QPushButton("Click here to ummark the tesxt",this);
    b2->setGeometry(10,60,280,40);
    b2->setFont(QFont("Times",18,QFont::Bold));
   
    b3=new QPushButton("Click here to remove the tesxt",this);
    b3->setGeometry(10,110,280,40);
    b3->setFont(QFont("Times",18,QFont::Bold));
    
    ledit=new QLineEdit("This is a line of text",this);
    ledit->setGeometry(10,160,280,30);
    
    connect(b1,SIGNAL(clicked()),ledit,SLOT(selectAll()));
     connect(b2,SIGNAL(clicked()),ledit,SLOT(deselect()));
      connect(b3,SIGNAL(clicked()),ledit,SLOT(clear()));
    
    
    
}



int main(int argc,char **argv)
{
QApplication a(argc,argv);
MyMainWindow w;
a.setMainWidget(&w);
w.show();
a.exec();

    
}