@suslucoder said in Double Spin Box Save to the file:

Is it possible to do it?

Is it possible to do what?

The fact that you divide your UI so that the data is presented on separate tabs/pages (which is fine) has nothing to do with whether it is possible to save data, nor whether you might adopt a QDataWidgetMapper approach.

@tomaschku said in Get Value of DoubleSpinBox into a double or float:

Code for checking Values:
ui->text_result->setText("Error! " + QVariant(a).toString() + "|" + QVariant(b).toString());

when I edit the Values with the DoubleSpinBoxes, then the Value a doesn't change. (i.e. It's 0.)

I think the problem is even worse than what is mentioned above.
double a = ui->input_a->value(); does not imply that when input_a changes it automatically updates a