Why must I re-declare a virtual function from an inherited class?

Question

I\'m working on a simple C++ program and am having a difficult time understanding a compiler error I was getting. The issue was caused by me attempting to create a derived class

Answer 1

When you declare a method in a derived class, you say to the compiler:

I want to override this method in this class

So if you don't declare a method in the derived class, you say:

I don't want to override this method; derived class's implementation is the same as the one in the base class

In your case, the base class declares them as pure virtual, so in this case it can be paraphrased:

I don't want to implement this method in this class

If you try to define a method but not declare it, you contradict yourself. The compiler detects that (to protect you from your own negligence).