Question

I have a derived derived class from an abstract class. The code is below. I have a FishTank class which is derived from an Aquarium and Aquarium is derived from item. My question is that should I put the definition of virtual int minWidth() const = 0; in aquarium again or is the code below sufficient?

class Item{
public:
   virtual int minWidth() const = 0;
};

class Aquarium: public Item{
public:
  virtual int calWidth() = 0;   // Pure virtual function.
};

class FishTank : public Aquarium{
    public:
       FishTank(int base1, int base2, int height);
       ~FishTank();
    int calWidth();
        int minWidth();
};

Answer 1

There’s no reason to do it again. It only serves to waste space and give you the opportunity to get compile errors from typos. 🙂 Once you inherit, it’s just like it had been there anyway.

However, you don’t actually ever implement it! Why? You’re missing const in FishTank:

int minWidth() const; // <-- const!