Access Specifiers and Virtual Functions

Question

What are the accessibility rules when virtual functions are declared under three different access specifiers defined by C ++ (public, private, protected) What is the meaning of each of them? Any simple code examples to explain the concept will be very helpful.

Answer 1

Access specifiers apply just like any other name when searching for a name. The fact that the function is virtual does not matter at all.

There is a common mistake that sometimes happens regarding virtual functions.

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// Brain compiled code ahead
struct A{
   virtual void f() {}
private:
   virtual void g() {}
protected:
   virtual void h() {}
};

struct B : A{
private:
   virtual void f() {}           // Allowed, but not a good habit I guess!
};

B b;
A &ra = b;

ra.f();    // name lookup of 'f' is done in 'A' and found to be public. Compilation 
           // succeeds and the call is dynamically bound
           // At run time the actual function to be called is 'B::f' which could be private, protected etc but that does not matter

Answer 2

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:

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Public - , / . , ( ) /.

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class A : [public | protected | private] B
{
};

// infront of B . "" , , , , ( ).

, class A : public B , , class A : private B .

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