Why can't a derived class call protected member function in this code?

Question

#include 

class Base
{  
protected:
    void somethingProtected()
    {
        std::cout << \"lala\" << std::endl;
    }
};

class Deri         


        

Answer 1

What you have done is illegal in C++. A protected member can not be accessed by an object of a class. Only member functions can access protected members. protected members behave just like private members except while inherited by a derived class. Consider the program given below to understand the difference between private, public and protected members.

class Base
{
    private:
    void somethingPrivate()
    {
        std::cout << "sasa" << std::endl;
    }
    public:
    void somethingPublic()
    {
        std::cout << "haha" << std::endl;
    }
    protected:
    void somethingProtected()
    {
        std::cout << "lala" << std::endl;
    }
};

class Derived : public Base
{
public:
    void somethingDerived()
    {
       Base b;
       b.somethingPublic();   // Works fine.
       somethingProtected();  // This is also fine because accessed by member function.
       //b.somethingProtected();  // Error. Called using object b.
       //somethingPrivate();      // Error. The function is not inherited by Derived.
    }
};