Virtual function inheritance

Question

I have a confusion about the inheriting the virtual property of a method.

Let's suppose we have 4 classes: class A, class B, class C and class D. The classes are inherited by this way: A -> B -> C -> D, where A is the base class.

By this time, I'm sure about this: Beginning the class method declaration with virtual in a base class (class A), makes the method virtual for all classes derived from the base class, including the derived ones of the derived classes. (B and C class methods determined to be virtual).

The confusion is here. What if, in the base class A, there wouldn't be any virtual member. Instead, let's say, that class B declares a method to be virtual. I assume, that this change would make the function virtual for all the derived classes that belong to the inheriting chain (C and D classes). So logically, B for C and D, is a sort of their "base class", right? Or am I wrong?

Answer 1

You're correct.

I think that in this case the best solution is to try:

#include <iostream>

using namespace std;

class A {
   public:
      void print(){ cout << "print A" << endl; };
};

class B: public A {
    public:
       virtual void print(){ cout << "print B" << endl; };
};

class C: public B {
     public:
        void print(){ cout << "print C" << endl; };
};

int main()
{
   A *a = new C();
   B *b = new C();

   a->print(); // will print 'print A'
   b->print(); // will print 'print C'

   return 1;
}