Implementing abstract class members in a parent class

Question

Is it possible to implement an abstract base class with members inherited from another parent class in C++?

It works in C#, so I tried doing it in C

Answer 1

ITalk contains the pure virtual function SayHi(), so if you want to be able to instantiate a class that derives from ITalk that class must implement SayHi().

class Child : public Parent, public ITalk
{
public:
  void SayHi() { std::cout << "Hi!" << std::endl; }
};

Alternatively, Parent can inherit from ITalk (but not Child) and the code you've posted will work.

Also, when implementing a base class with virtual functions you must define virtual destructors for those base classes. So ITalk should be:

class ITalk
{
public:
    virtual void SayHi() = 0;
    virtual ~ITalk() {}
};

If you don't do that the following produces undefined behavior

ITalk* lChild = new Child();
lChild->SayHi();
delete lChild;