How does compiler implements inheritence?

Question

Possible Duplicate:
C++: rationale behind hiding rule

Suppose I have a code:

class  A
{       
    public:
    void f(int s) {}
};



class B:public A
{      
    public:
    void f() {}
};

int main()
{      B ob;
   ob.f(4);
}

Then in this case compiler generates an error that "no matching function for call to ‘B::f(int)'" But class B has inherited A as public so B must have the function "void f(int s)". Dont know why compiler is generating error here?

You should not ask "how does the compiler" but "what are the rules in C++ that...". — Mark Garcia, Nov 29 '12 at 07:58

score 5 · Answer 1 · answered Nov 29 '12 at 07:55

5

That is because B defines a different f, which hides the f inherited from A. If you want both available in B (which is likely), you must bring it into scope with a using-declaration:

class B : public A
{
  void f() {}
  using A::f;
};

This behaviour is specified in [class.member.loopkup], especially paragrah 4.

answered Nov 29 '12 at 07:55

Angew is no longer proud of SO

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That is, if you want to overload `A::f(int)' with `B::f()`, you must do the above. – Mark Garcia Nov 29 '12 at 07:56
+1 "Hiding" is the correct term here. – In silico Nov 29 '12 at 07:57

score 3 · Answer 2 · answered Nov 29 '12 at 07:55

3

When you declare void f() in B, this hides the void f(int) inherited from A. You can bring it back into scope with using:

class B: public A
{      
public:
    void f() {}
    using A::f;
};

answered Nov 29 '12 at 07:55

NPE

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These two answers are very much the same. – Mark Garcia Nov 29 '12 at 07:57

score 0 · Answer 3 · answered Nov 29 '12 at 07:57

0

This is called Hiding - you can check the C++ FAQ Entry. It describes the problem and the solution.

answered Nov 29 '12 at 07:57

user93353

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How does compiler implements inheritence?

3 Answers3