How to pass data between forms in qt

Question

I have a Mainwindow which has four buttons,all these four buttons are connected to "clicked()" signal. When we click on the button it goes to another widget which replaces the mainwindow(using stacked layout). I want to pass the name of the button to the widget so that I can use that value and append it to a label in the widget. I tried passing values to the widgte using the following method:

mainwindow.h

public:
    explicit MainWindow(QWidget *parent = 0);
    QStackedLayout *stackedLayout;
    QLineEdit* lineEdit();

mainwindow.cpp

QLineEdit* MainWindow::lineEdit()
{
    //buttonName is a QLineEdit on the main form which is hidden and value is being set when a button is clicked
    std::string text=ui->buttonName->text().toUtf8().constData();
    std::cout<<"Button Name passed from main window is"<<text<<std::endl;

    return ui->buttonName;
}

SecondForm.cpp

    MainWindow mainWind;
    std::string text=mainWind.lineEdit()->text().toUtf8().constData();
    std::cout<<"The name of the button is"<<text<<std::endl;

This is the approach that I am following. The data is not being returned to the second form. Is it because I am setting the value of the QLineEdit after the button is clicked and the value is not being stored anywhere? Could you let me know what I am missing here.

Answer 1

In your on_button_clicked() slot for each button, you could signal the text() for the button clicked to the new widget.

//Your signal declaration in MainWindow.h
void signalToWidget( QString buttonText );

/*The slot in your widget to handle the text (you may need to subclass your widget to add this functionality*/
void slotSetText( QString buttonText )
{
    widgetElement->setText( buttonText );
}

//connect in MainWindow constructor
QObject::connect( MainWindow, SIGNAL( signalToWidget( QString ) ),
                  widget, SLOT( slotSetText( QString ) ) );

void MainWindow::onButton1Clicked()
{
    emit signalToWidget( ui->button1->text() );
}