How to use superclass constructor in Qt Creator?

Question

As you might know, classes in Qt Creator are part of the project as class.h and class.cpp files. Let's presume that we have two classes A (a.h, a.cpp) and B (b.h, b.cpp), and that B inherits A. How can I use the A's constructor when using B's constructor?

Answer 1

A's constructor is automatically called when you construct a B.

If you need to pass parameters to A's constructor to have it work correctly explicitly call it in B's constructor:

B::B()
 :A(Blah)
{
}

This would be common when A is QObject and you want the ownership stuff to happen correctly, you'll pass in the parent pointer in B's constructor and pass that onto A's:

B::B(QObject* parent_)
 :A(parent_)
{
}

This is nothing to do with Qt and is a pure C++ concept.