Question

I saw code in a derived class recently in which the programmer put virtual in front of the functions overridden. Is this common? I thought it was very odd and it kind of caught me off guard.

Edit: I’m not asking what virtual does, I’m asking why someone would put virtual in a derived class that is already overriding virtual functions in its base class.

EX:

class B {
 public:
  virtual void foo();
  ....
};

class D : public B {
 public:
  virtual void foo(); // could have just put void foo();
  ...
};

Answer 1

virtual is needed for overrideable functions at the highest (least derived) level. It is optional, but harmless at lower (more derived) levels. It’s good for self-documenting the code.