Topical Information

The purpose of this quiz is to give you a chance to focus your knowledge of advanced inheritance and polymorphism in C++.

Quiz Information

Questions

1.  

   TRUE ✓		FALSE ✗		The virtual keyword is used for both polymorphism and (some) multiple inheritance.
   TRUE ✗		FALSE ✓		Multiple inheritance is a breeze: just list two ancestors and you are done.
   TRUE ✓		FALSE ✗		It is very applicable and necessary in real-world problems, too (see the hover-craft and how it is both a land and water vehicle).
   TRUE ✗		FALSE ✓		I try to multiply inherit something everyday.

2.  

   TRUE ✗		FALSE ✓		Inheritance applies to all member variables, methods, and friends.
   TRUE ✓		FALSE ✗		This rule applies to operator functions, too.
   TRUE ✗		FALSE ✓		Function objects, however, cannot participate in inheritance at all.

3.  

   TRUE ✓		FALSE ✗		When inheriting from a base with a static data member, all derived classes share the same static member.

4.  

   TRUE ✓		FALSE ✗		An abstract class is one which contains pure virtual method(s).
   TRUE ✓		FALSE ✗		Pure virtual methods are methods with no definition.
   TRUE ✓		FALSE ✗		This is achieved by setting the prototype = 0.
   TRUE ✓		FALSE ✗		This says in effect "this method will never be defined" which would, of course, be impossible to call and so the compiler won't allow objects to exist of this class.
   TRUE ✓		FALSE ✗		We can, however, make pointers to non-abstract derivatives of the abstract class.

5.  

   TRUE ✓		FALSE ✗		Composition is a situation where one class has at least one data member which is of another class type.
   TRUE ✓		FALSE ✗		This is known as the "HAS A" relationship in software engineering.
   TRUE ✓		FALSE ✗		Inheritance is a situation where one class is a more specific sub-group of another class.
   TRUE ✓		FALSE ✗		In software engineering, this is known as the "IS A" relationship.

6.  

   TRUE ✓		FALSE ✗		When inheriting, we normally use the inheritance mode public.
   TRUE ✓		FALSE ✗		However, we can also substitute private or protected there.
   TRUE ✓		FALSE ✗		A private inheritance mode causes all parent members to be private members of the child when viewed from the child class' descendants or outside the hierarchy.
   TRUE ✗		FALSE ✓		Likewise, a protected inheritance mode causes all parent members to be protected members of the child when viewed from the child class' descendants or outside the hierarchy.
   TRUE ✓		FALSE ✗		Both of these can prove terribly troublesome and are often avoided.

7.  

   TRUE ✓		FALSE ✗		The actual type of object at the end of a polymorphic base pointer can be determined at run time.
   TRUE ✓		FALSE ✗		To do so, we need to use either the typeof function or the dynamic_cast operator.
   TRUE ✓		FALSE ✗		The function is in the typeinfo library and returns a type_info structure.
   TRUE ✓		FALSE ✗		To identify the type, you can compare the return value of the type_info structure's name method to a string containing the name of the type you desire.
   TRUE ✗		FALSE ✓		Such names are just what you'd expect them to be and so this is an easy method of identification.
   TRUE ✓		FALSE ✗		When using dynamic_cast, though, you simply check if the result of the cast is nullptr or not.
   TRUE ✓		FALSE ✗		If it's nullptr, the object was NOT of the desired type.