C++ Quiz #2

This is a test of your knowledge of C++, not of your compiler’s knowledge of C++. Using a compiler during this test will likely give you the wrong answers, or at least incomplete ones.

1. Using the code below as a reference, explain what behavior should be expected of each of the commented lines, please keep your answer very short.

   struct Base {
       virtual void Arr();
   };
   struct SubBase1 : virtual Base { };
   struct SubBase2 : virtual Base {
       SubBase2(Base*, SubBase1*);
       virtual void Arr();
   };
   
   
   struct Derived : SubBase1, SubBase2 {
       Derived() : SubBase2((SubBase1*)this, this) { }
   };
   SubBase2::SubBase2(Base* a, SubBase1* b) {
       typeid(*a);                 //1
       dynamic_cast<SubBase2*>(a); //2
       typeid(*b);                 //3
       dynamic_cast<SubBase1*>(b); //4
       a->Arr();                   //5
       b->Arr();                   //6
   }
   

2. Using the code below as a reference, explain what behavior should be expected of each of the commented lines?

   template<class T> class X {
       X<T>* p;  //1
       X<T>  a;  //2
   };