[QT 5.5.1] TextEdit i Przycisk button

#include <QApplication>
#include <QTextEdit>
#include <QPushButton>
#include <QWidget>


class CProgram
    : public QWidget
{
   
public:
    CProgram( QWidget * parent );
   
public slots:
    void pokaz_text();
private:
    QTextEdit * tex;
    QPushButton * buton;
   
};
CProgram::CProgram( QWidget * parent = 0 )
    : QWidget( parent )
{
    tex = new QTextEdit( this );
    buton = new QPushButton( "POKAZ TEXT", this );
    tex->setGeometry( 5, 5, 200, 150 );
    buton->setGeometry( 100, 160, 100, 20 );
   
    QObject::connect( buton, SIGNAL( clicked() ), tex, SLOT( pokaz_text() ) );
}
void CProgram::pokaz_text()
{
    tex->setText( "kkkk" );
}

int main( int argc, char * argv[] )
{
    QApplication a( argc, argv );
    CProgram cpr;
    cpr.show();
    return a.exec();
}