The parent parameter in QT

A constructor with arguments to the parent class is called in the constructor initialization list of the derived class in order to initialize the member variables inherited from the parent class. Because these variables cannot be initialized directly, they can only be initialized in this way.

In Qt, a member variable in MainWindow (a pointer to the parent component, assuming p) cannot be initialized directly, only the Qmainwindow (parent) is called in the initialization list, and the value of the parameter parent is passed to P indirectly, so that P completes the initialization.

The parent parameter in QT