Enable a bool variable by pressing a button in Qt - c++

Question

How to link a variable to a push button so it is enabled as true for first time when the push button is pressed, and made false when it is pressed for the second time, and so on?
I want to use it because in my program a certain loop should be executed when the push button is pressed so that the variable is enabled as true.
Can someone help me?

Answer 1

In order to achieve that, you need to connect the clicked() signal (inherent to a QPushButton) to a slot of yours. Then, in this slot, you just need to change a boolean of your object each time you enter this slot. This is the code you need.
In your .h file :
private:
bool bForButton;
QPushButton* m_button;
public slots :
void onClicked();
In your .cpp :
MyClass::MyClass()
{
bForButton = false;
m_button = new QPushButton(this);
connect(m_button , SIGNAL(clicked()), this, SLOT(onClicked()));
}
void MyClass::onClicked()
{
bForButton = !bForButton;
}
This way, you notice that we change the boolean to its opposite, so it will change each time you click the button, as required.

Answer 2

You can display a button that keeps the state (checked or not) so each time you click on it its state change and the user can see the current state.
You can achieve that by setting your button checkable setCheckable(true) and test in your loop the value of isChecked(). The button will keep the checked state and update on click automatically so you don't need any extra code.

Answer 3

The QPushButton has such variable, i.e. the checked property.
You can connect the loop you need run to the toggled signal:
auto button = new QPushButton(this);
button->setCheckable(true);
...
connect(button, &QAbstractButton::toggled,
this, &ThisClass::executeLoop);
...
void ThisClass::executeLoop(bool checked) {
if (!checked) return;
.... your function body
}
http://doc.qt.io/qt-5/qabstractbutton.html#checked-prop
This is more in the mindset of Qt: don't loop/spin/lock/..., just react to events triggered by the framework (i.e. connect signals to slots).