1.1.17.3 template and friend

• There are three different kinds for a template class: non-template friend, Bound-template, unbound-template. Below is non-template friend function counts(); The counts is not invoked by an HasFriend obj.
  template<typename T> 
  class HasFriend{ 
  friend void counts(); 
  }
• Bound-template friend function. You need to define explicit specialization for the friends you plan to use.
  template<typename T> 
  class HasFriend{ 
  friend void reports(HasFriend<T> &); 
  } 
   
  void reports(HasFriend<int> &hf){ 
  cout <<hf.item<<endl; 
  } 
  void reports(HasFriend<short> &hf){..} 
  void reports(HasFriend<char> &hf){..} 
  //explicit specialization for the type you plan to use.
• A better bound-template, reports has <> after it. and you don’t need redifne reports many time like previous codes.
  1) template <typename T> void report(T &); 
   
  2)template<typename TT> 
  class HasFriend{ 
  friend void reports<>(HasFriend<TT> &); 
  } 
   
  3) 
  template<typename T> 
  void reports(T &hf){ 
  cout <<hf.item<<endl; 
  }
• non-bound friend template.
  template<typename T> 
  class ManyFriend{ 
  template<typename C, typename D> 
    friend void show(C& , D&); 
  }; 
   
  template <typename C, typename D> void show2(c& c, D& d){ 
  cout<<c.item<<d.item<<endl; 
  } 
  ManyFriend<int> mi; 
  ManyFriend<double>md; 
  show2(mi,md);