Declare a Template Specialization as a Friend of a Class Template

You can declare a template specialization as a friend of a class template. In this example, the class template Vector declares the specialization C

 template  class C{/*...*/};template  class Vector{public:  //...  friend class C; //other specializations are not friends of Vector};

Each specialization of Vector has the specialization C, C etc., are not friends of Vector.