virtual function in parent of parent class

Question

The following code is late binding test() method but shouldn't it bind early? because test() method is not virtual in class B(but in class A), and we are using pointer of class B.

class A{
    public:
        virtual void test(){
            cout<<"test a";
        }
};
class B : public A{
    public:
        void test(){
            cout<<"Test b";
        }
};
class C: public B{
    public:
        void test(){
            cout<<"test c";
        }
};
int main(){
    B *bp;
    C objc;
    bp = &objc;
    bp->test();  // test c
}

`test` is virtual in all classes here; the `virtual` keyword does not need to be repeated. — MicroVirus, May 12 '16 at 09:33

score 5 · Answer 1 · answered May 12 '16 at 09:35

Once a function has been declared virtual in a class, it's always virtual in the classes that inherit from that class, whether you use the virtual keyword or not.

So in your class C, the test() function is actually overriding B and A's own test() functions.

score 4 · Answer 2 · edited May 12 '16 at 11:02

N4296, 10.3§2 (draft version):

If a virtual member function vf is declared in a class Base and in a class Derived, derived directly or indirectly from Base, a member function vf with the same name, parameter-type-list (8.3.5), cv-qualification, and ref-qualifier (or absence of same) as Base::vf is declared, then Derived::vf is also virtual (whether or not it is so declared) and it overrides Base::vf.

Emphasis by me.

A virtual function remains virtual in all derived classes, regardless if it is declared as virtual in the derived classes.

virtual function in parent of parent class

2 Answers2