C + + foundation Guidelines on how to visit sub-class object type father-members What kind of father class target? But you can use : (A class B : public) A new *pa = A; B = static_cast<B*> *pb (pa); Do, the compiler links, but this is wrong. A target should not include B target. --> Static_cast<B*> (pa); How to understand? --> Not right? ? If the guidelines should be converted to Class-derived class, the derived class should be allowed at the base class Object ah, this polymorphic form of bars should dynamic_cast A*pa=new B; B*PB=static_cast<B*> (pa); I doubt why they did not directly target the basic category at the derived classes of objects, changing the benefits? ? It should be like this? 14.00 A; Class B : public A{ Public : Mem b (); } Class C : public A{ Public : Mem c (); } ..... A *a; If (. . . ) A=new B; Else A=new C ...... French b=dynamic_cast<B*> (a); If (b) B->b (); [ Closed window ]