Question

IF both methods are declared as virtual, shouldn’t both instances of Method1() that are called be the derived class’s Method1()?

I am seeing BASE then DERIVED called each time. I am doing some review for an interview and I want to make sure I have this straight. xD

class BaseClass
{
public:
    virtual void Method1()  { cout << "Method 1 BASE" << endl; }
};

class DerClass: public BaseClass
{
public:
    virtual void Method1() { cout << "Method 1 DERVIED" << endl; }
};


DerClass myClass;
    ((BaseClass)myClass).Method1();
    myClass.Method1();

Method 1 BASE
Method 1 DERVIED

Answer 1

What you are seeing here is called “slicing”. Casting an object of the derived class to the base class “slices off” everything that is not in the base class.

In C++ virtual functions work correctly only for pointers or references. For your example to work right, you have to do the following:

DerClass myClass;
((BaseClass *) &myClass)->Method1();

Or you could do

BaseClass *pBase = new DerClass;
pBase->Method1();