why we use Using Declaration in derived class?

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Why shall I use the “using” keyword to access my base class method?

using declaration introduces a name of data member or member function from a base class into the scope of derived class which is implicitly accomplished when we derive a class from base class, then what is the utility of using "using declaration"?

i want to know in depth the use of using declaration in classes in c++.

Could you add an example? I rarely use "using" in derived classes. — Tilman Vogel, Jun 23 '11 at 08:37
See this thread: http://stackoverflow.com/questions/3544824/using-declaration-derived-class — Ozair Kafray, Jun 23 '11 at 08:40
http://stackoverflow.com/questions/5896908/understanding-simple-c-inheritance/5896943#5896943 and http://kera.name/articles/2010/08/overcoming-name-shadowing-in-c/ — Lightness Races in Orbit, Jun 23 '11 at 08:42

score 4 · Answer 1 · answered Jun 23 '11 at 08:39

struct Base()
{
   void f(char);
};

struct Derived: Base
{
   void f(int);
};

int main()
{
   Derived d;
   d.f('a');
}

Which do you think will be called? It appears that f(int) is called, because the name f hides the name f in Base. So you need a using-declaration to enable it.

struct Derived: Base
{
   using Base::f;
   void f(int);
};

Now f(char) will be called.

That's one example. HTH

why we use Using Declaration in derived class?

1 Answers1