title: Why the virtual destructor in derived class is empty?
body: <p>I have one question, I see that in some codes, the virtual destructor in derived class is empty, then why we need it since it does nothing? Is it used to call the destructor in base class and without it, the destructor cannot be called? or it is just a notation to tell the code reader that this destructor is virtual which makes code much easier to read? Thanks! </p>