class MainWindow : public QMainWindow
{
 
...
 
public:
    void put (QString s);
 
private slots:
    void on_pushButton_clicked();
 
...
 
};

void MainWindow :: put (QString s)
{
    ui->textEdit->append (s);
}
 
 
void MainWindow::on_pushButton_clicked()
{
    bool b = ui->checkBox->isChecked();
    if (b)
       put ("Zapnuto");
    else
        put ("Vypnuto");
    ui->checkBox->setChecked (! b);
 
 
    QString s = ui->lineEdit->text ();
    put ("Text = " + s);
    ui->lineEdit->setText (s + " ...");
 
    int n = ui->spinBox->value ();
    put ("Number = " + QString::number (n));
    ui->spinBox->setValue (n+1);
 
    double d = ui->doubleSpinBox->value ();
    put ("Real number = " + QString::number (d));
    ui->doubleSpinBox->setValue (d+0.5);
 
    put ("");
}

Zdrojové texty priklad2.zip