Thread: Pointing to derived class

Point is the base class and ThreeD is the derived class. I would like to create a new object dynamically from the derived class via the following code:

Code:

int main()
{
	Point *ptr = new ThreeD();
	(*ptr).setXY(1,1); //base member function
	(*ptr).setZ(1); //derived member function
	(*ptr).display(); //polymorphic function

	return 0;
}

The problem is that setZ(), a member function of the derived class, is unable to be called. Apparently the class created is that of the base class. What did I do wrong? Why isn't the object of the derived class?