How to Set a Default Value for a check Box Group in a Qt Widget Application in C++

In this article, we show how to set a default value for a check box group in a Qt widget application in C++.

An example of a group of check boxes is shown below with the first choice and the last choice selected as the default values for the group.

This is shown below.

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With check boxes, 1 or more elements can be selected by default. This contrasts with radio buttons, in which only one element may be selected as default for the group.

So how do we select a default value for a check box group?

So in order to set the default value for a check box group in a Qt widget application, we go to the "widget.cpp" header file and add in a line, which checks the check box(es) that you want selected by default.

#include "widget.h" #include "ui_widget.h" Widget::Widget(QWidget *parent) : QWidget(parent) , ui(new Ui::Widget) { ui->setupUi(this); ui->checkBox->setChecked(true); ui->checkBox_4->setChecked(true); } Widget::~Widget() { delete ui; } void Widget::on_pushButton_clicked() { //Main code }

The lines we add are, ui->radioButton->setChecked(true); and ui->checkBox_4->setChecked(true);, which uses the setChecked() function to create default values for the check box group.

The setChecked() function takes in the parameters of either true or false. When creating a default value, true must be passed in as its parameter.

checkBox refers to the name of the check box that you want selected. In this case, it is the first check box that we select as the default selected item. checkBox_4 refers to the fourth check box, which we also want selected by default.

Let's say there are 4 check boxes in a certain check box group. These 4 check boxes have the following names: checkBox, checkBox_2, checkBox_3, and checkBox_4.

If we want to select the second check box by default, then you would add the following line into code, ui->checkBox_2->setChecked(true);

If we want to select the third check box by default, then you would add the following line into code, ui->checkBox_3->setChecked(true);

If we want to select the fourth check box by default, then you would add the following line into code, ui->checkBox_4->setChecked(true);

Keep in mind that if you have several check box groups, you can select default values for each one. But you must make sure that each group of check boxes is delineated in the software as its own group.

So if you have 8 check boxes on a certain user interface in your Qt widget application and the first check box group is check boxes 1-4 and the second check box group is check boxes 5-8, then you can select default check boxes from 1-4 for the first group and default check boxes from 5-8 for the second group.

And this is how to set a default value for a check box group in a Qt widget application in C++.

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