Question

Let’s say I have a base class A and class B derives from it. Class C from B and so on …..
Y from Z.

Who will be responsible for initializing the data members of class A, when I instantiate class Z?

Answer 1

When you inherit from a class, the base class’s constructor is called prior to the derived class’s. You can control what gets passed to it using the initializer list:

struct A
{
    A();
    A(int);
}

struct B
{
    B(){} // A() is called implicitly.
    B(int x) : A(x) {} // A(int) is called explicitly.
}