Overriding vs Virtual

Question

What is the purpose of using the reserved word virtual in front of functions? If I want a child class to override a parent function, I just declare the same function such as

Answer 1

If the function were virtual, then you could do this and still get the output "2":

Parent* a = new Child();
a->say();

This works because a virtual function uses the actual type whereas a non-virtual function uses the declared type. Read up on polymorphism for a better discussion of why you'd want to do this.