Base class pointer vs inherited class pointer?

Question

Suppose I have a class Dog that inherits from a class Animal. What is the difference between these two lines of code?

    Animal *a         


        

Answer 1

It makes no real difference at run time, as the two instances are the same. The only difference is at compile time, where you could call for example d->bark() but not a->bark(), even if a actually contains a dog. The compiler considers the variable to be an animal and only that.