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Asked: 2026-05-31T13:30:51+00:00

this is a question for programming with Qt/C++. I have a combo box with

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this is a question for programming with Qt/C++. I have a combo box with two items. If current index for selection is 0, then no QLineEdit should be displayed in layout below the combo box. If it is 1, a QLineEdit should appear. It should disappear again if index is 0 again.
Notably, other elements in the layout should not be affected by the change. Values already entered by user in other QineEdit should remain in place.

Is it possible to dynamically modify widget? How did you procede?

Kind regards.

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1 Answer

  1. Editorial Team

    All QWidget objects have a function called hide().

    You can attach a signal to the currentIndexChanged signal of the combo box, and in that function you implement whatever logic you have in mind and invoke the method hide of your QLineEdit.

    The only problem with this approach is that a Qt Widget, when hidden, doesn’t occupy any space on the screen, and this can lead to layout changes (depending on how you’ve programmed your layout, some other widgets can move a bit, for example). To prevent that you can make another Widget appear where the QLineEdit were (perhaps invoking the show() function, and placing the ‘placeholder’ on the same container that the LineEdit was), only to occupy its space and keep it there, or you can use a QStackedWidget add the two Widgets there and change its index.

    I would recommend that you read the following example, it has some useful insight on dynamically changing things: Qt Extension Example.

    Also, when in doubt, take a look in the other examples, they are really well documented and cover a lot of important topics on Qt.

    Good luck with your code 🙂

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