Question

Here is what I have:

class Abstract
{
public:
  virtual bool isThis(Abstract*);
};

class FileType:public Abstract
{
public:
  bool isThis(FileType* ptr)
  {
    return false;
  }
};

And this is what Visual Studio sais:

Thanks a lot

Answer 1

First, if you do not provide code for the function in Abstract, you have to make it virtual pure (adding = 0at the end). Then, the signature of the function in the derived class has to be the same (i.e. accepts an Abstract* parameter instead of FileType*).

I strongly suggest you to read some C++ manuals before. It will save you a lot of trouble.