struct  A { virtual ~A() = default; };
struct  B : A { void fun1(){ std::cout << "B\n"; }};
struct  C : A { void fun2(){ std::cout << "C\n"; }};



int main()
{
   srand(time(NULL));
   A* ptr = nullptr;
   if (rand() % 2){
       ptr = new B;
   } else {
       ptr = new C;
   }


   B* b_ptr = dynamic_cast<B*>(ptr);
   if(b_ptr){
       b_ptr->fun1();
   } else {
       dynamic_cast<C*>(ptr)->fun2();
   }

    delete ptr;


   return 0;
}