Multilevel protected Inheritance in C++

Question

I'm having a scenario where i'm implementing multilevel inheritance but first level inheritance is specified as protected inheritance , but it is giving me compilation issue.

class A
{
 protected:
    int a1;
};

class B: protected A
{
 protected:
    int b1;
};

class C: public B 
{
public:
    C()
    {
        a1=10;
        b1=20;
        cout<<a1<<b1<<endl;
    }
};

int main()
{
    C c;   //can access A class protected data
    A* a= new C; //compilation error: cannot cast 'C'to its protected base class 'A'
}

My issue is when i do inheritance using protected access specified ,I'm able to access all A Class data members then why can't I'm able to have a pointer of A class type holding C object?

Everybody knows that `C` is a `B` but only `B` and `C` know that `B` and `C` are `A`s. `main` is not part of `B` or `C`, so it cannot make use of that relationship. — user4581301, Sep 28 '21 at 15:41
It is not in **the scope of main** where the protected member data is accessed. That would be in the scope of `C::C()`. — StoryTeller - Unslander Monica, Sep 28 '21 at 17:41

score 2 · Answer 1 · answered Sep 28 '21 at 15:34

2

main is not privy to the inheritance relationship due to its protected status.

class B: protected A

is what makes it inaccessible outside of B:: and C::

answered Sep 28 '21 at 15:34

Captain Giraffe

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Multilevel protected Inheritance in C++

1 Answers1