cannot call base class protected functions?

Question

I cant call protected function in my base class. Why? It looks something like this: ``` class B : B2 { public: virtual f1(B*)=0; protected: virtual f2(B*) { codehere(); } } class D : public B { public: virtual f1(B*b) { return f2(b); } protected: virtual f2(B*b) { return b->f2(this); } } ``` In msvc I get the error error C2248: 'name::class::f2' : cannot access protected member declared in class 'name::class' In gcc I get error: 'virtual int name::class::f2()' is protected. Why is that? I thought the point of protected members is for derived classes to call.

Accepted Answer

Protected member functions can only be called inside the base class or in its derived class. You cannot call them outside your class. Outside calling means calling a member function of a class-typed variable.

So

```
virtual f1(B*b) { return f2(b); }
```

is ok, because f2 operates on the class itself. (called inside)

But

```
virtual f2(B*b) { return b->f2(this); }
```

won't compile, because f2 operates on b not the class D itself. (called outside) It's illegal.

To fix it B::f2 should be public.

cannot call base class protected functions?

Solution

Problem