QComboBox of Qt Programming: Common Functions and Sample Code

Introduction

The QComboBox widget, which provides a drop-down list of items for users to choose from.

Creating a QComboBox

To create a QComboBox, you can use the following code:

QComboBox *comboBox = new QComboBox(parent);
comboBox->addItem("Item 1");
comboBox->addItem("Item 2");
comboBox->addItem("Item 3");

This code creates a new QComboBox object and adds three items to it. The parent argument specifies the parent widget of the QComboBox, which is typically the main window or a container widget.

Retrieving the Selected Item

To retrieve the currently selected item in a QComboBox, you can use the currentText() function. Here’s an example:

QString selectedItem = comboBox->currentText();

The currentText() function returns the text of the currently selected item as a QString. You can then use this value in your application as needed.

Handling Selection Changes

If you want to perform some action whenever the user selects a different item in the QComboBox, you can connect the activated() signal to a slot. Here’s an example:

connect(comboBox, SIGNAL(activated(const QString&)), this, SLOT(handleSelectionChange(const QString&)));

In this code, the activated() signal is emitted whenever the user selects a different item. It is connected to the handleSelectionChange() slot, which is a custom function you can define to handle the selection change event. The selected item is passed as a parameter to the slot function.

Conclusion

The QComboBox widget is a versatile tool in Qt programming, allowing users to select items from a drop-down list.