How to connect a signal in Qdialog to a slot in QMainwindow - qt

Question

I work with QT Creator 4.9.1 and i've made a gui with the designer. I have a MainWindow with a stackedWidget and round about 60 pages, inside my mainwindow i have a button, with the onButton_clicked signal i open a dialog(show picture) to insert a number to set the page the user want to see inside the mainwindow.
My Problem is that the SIGNAL comes from the Dialog with the name on_pushButton_Enter_clicked and my SLOT is inside my mainwindow with the name setCurrentIndex(). I,ve read the post's: "How to Connect Signal from MainWindow to Slot in Dialog" and "Qt connect mainwindow and dialog using signal and slot".
But that doesn't help me because my dialog doesn't know about my mainwindow and i don't know how i can connect them.
Signal:
Dialognummer_eingeben.h
...
signals:
void enterButtonPressed();
...
void Dialognummer_eingeben::on_pushButton_Enter_clicked()
{
QString text = ui->lineEdit_Dialognummer->text();
ui->lineEdit_Dialognummer->setText("");
this->reject();
emit enterButtonPressed();
}
Slot:
Terminal::Terminal(QWidget *parent) : QMainWindow(parent), ui(new Ui::Terminal)
{
ui->setupUi(this);
QObject::connect(&dialog, SIGNAL(enterButtonPressed()), this, SLOT(setCurrentIndex()));
}
void Terminal::setCurrentIndex()
{
int num = dianr.getNum();
QString strNum = QString::number(num);
switch(num)
{
....
}
}
Edit: 1. Add signal and slot code
2. Make some changes inside the code

Answer 1

inside my mainwindow i have a button, with the onButton_clicked signal i open a dialog(show picture) to insert a number to set the page the user want to see inside the mainwindow.
You have to additionally add a signal in your dialog class which should be emitted once enter button was pressed, using on_pushButton_Enter_clicked as a function is not enough. Add a signal in the dialog class, like "enterButtonPressed()" and emit it in the function on_pushButton_Enter_clicked.
Inside the mainwindow (at some point where the dialog is created) add this line:
connect(dialog, SIGNAL(enterButtonPressed()), this, SLOT(SlotNameWhichShouldGetCalled()));
EDIT: Even if the above solution should work, a better solution came to my mind.
You generally should use the QDialog::accepted signal to connect to (see https://doc.qt.io/archives/qt-4.8/qdialog.html#accept).
Concrete steps:
In on_pushButton_Enter_clicked() at the bottom of the code add accept() instead of this-reject() (I assume you want the dialog to be closed succesful and not as rejected?)
Connect to the QDialog::accepted() signal by adding
QObject::connect(&dialog, SIGNAL(accepted()), this, SLOT(setCurrentIndex()));
Additionally ensure that you have no error in the connect(...) function. If the signal/slot is not found or is not matching you should see something in your application output in Qt Creator