Covariant Returen Types (covariant return type)

The base class virtual Func Returns a Class (class super) of PTR or ref, and the subclass override of the virtual Func return type can be changed to PTR or ref for that class subclass (class Sub:public Super).

classbase{ Public:    Virtualbase* Clone ()Const{return NewBase (* This); }    Virtual~Base () {}};classDerived: Publicbase{ Public:    Virtualbase* Clone ()Const{return NewDerived (* This); }    Virtual~Derived () {}};intMain () {Derived D; Base* Bptr =D.clone (); Derived* DPtr = dynamic_cast<derived*>(BPTR); if(!dPtr) {        DeletedPtr; DPtr=nullptr; //Throw Exception ...    }    return 0;}

Switch
......

 class  Derived: public   base{ public  :  virtual  derived* Clone () const  {return  new  Derived (*this  );  virtual  ~derived () {}};  int      main () {Derived D;    Derived  * dPtr = D.clone ();  return  0  ;}  

classCherry {};classBingcherry: PublicCherry {};classcherrytree{ Public:    Virtualcherry* pick ()Const{return NewCherry ();}};classBingcherrytree: Publiccherrytree{ Public:    Virtualbingcherry* pick ()Const{return NewBingcherry ();}};

Covariant Returen Types (covariant return type)