Chapter 11 – Exam Questions | Inheritance, Polymorphism, And

Starting Out with Visual C#, 5e (Tony Gaddis)

Chapter 11 Inheritance, Polymorphism, and Interfaces

TRUE/FALSE

1. When an "is a" relationship exists between objects, it means that the specialized object has all of the characteristics of the general object plus additional characteristics that make it unique.

2. Inheritance involves a base class and a relative class.

3. You can think of a derived class as an extended version of some base class.

4. New fields, properties, and methods cannot be added to a derived class unless these elements already exist in the base class.

5. When designing an object-oriented program, the best approach is to define a base class to hold all the general data about a group of similar objects and then define derived classes for each specific type of object.

6. Only methods in a derived class can directly access the base class's private members.

7. When program code instantiates a derived class object, the base class constructor executes first, followed by the derived class constructor.

8. If a base class does not have a parameterless constructor, its derived class constructor must use the notation base(parameterList) to call one of the base class's constructors.

9. If a reference to a base class object calls a method that has been overridden by a derived class, the derived class's version of the method is the one that executes.

10. Properties in a base class can be overridden in the same way that methods can be overridden.

11. If a derived class introduces additional methods, properties, or fields, a base class reference variable cannot access them.

12. You cannot assign a base class reference to a derived class variable.

13. A method that accepts a base class variable as a parameter cannot accept a derived class variable as a parameter.

14. A class that is not intended to be instantiated but is to be used only as a base class is called a concrete class.

15. A statement that tries to use the new operator to instantiate an abstract class will not compile.

16. If you want to create an abstract read-only property, leave out the set accessor.

17. An extension method is a static method that extends an existing class or data type.

18. An extension method can only have one parameter.

19. All the parameters in an extension method must be preceded by the this keyword.

20. Extension methods can be applied to classes, structs, and interfaces.

21. An interface specifies behavior for a class.

22. An interface cannot be instantiated but rather is implemented by other classes.

23. An interface specifies methods and properties that a class must have and also specifies how that class must implement those methods and properties.

24. When declaring a class that inherits from a base class and implements an interface, the name of the base class must appear first after the colon in the derived class header.

MULTIPLE CHOICE

1. Which of the following is a specialized version of a generalized food substance?

2. When one object is a specialized version of another object, there is a(n) __________.

3. In object-oriented programming, __________ is used to create an "is a" relationship among classes.

4. In object-oriented programming, the __________ is more general than classes related to it.

5. The __________ inherits fields, properties, and methods from the base class without any of them having to be rewritten.

6. Base classes are sometimes called superclasses and derived classes are sometimes called __________.

7. Which of the following is a class header that indicates a class named Amphibian is being defined and it is derived from the Animal class?

8. When you want to make sure a specific constructor from the base class is used, the derived class constructor must explicitly call the base class constructor using the __________.

9. The __________ keyword declares that a derived class is allowed to override the current method in the base class.

10. The __________ keyword declares that a method in the derived class overrides a method in the base class.

11. The term __________ refers to an object's ability to take different forms.

12. When a derived class method has the same name as a base class method, it is often said that the derived class method __________ the base class method.

13. To allow a property to be overridden, you must include the virtual keyword in the property's declaration in the __________ class.

14. To override a property in the __________ you write the override keyword in the property declaration.

15. A variable declared as a base class type can only be used to reference members declared in the __________.

16. A class that is not intended to be instantiated but is to be used only as a base class is called a(n) __________.

17. To declare a class as abstract, you use the __________ keyword in the class header.

18. A class that is not abstract is sometimes called a(n) __________ class.

19. A(n) __________ method is a method with no body that appears in a base class and must be overridden in a non-abstract derived class.

20. A(n) __________ property is a property that appears in a base class and must be overridden in a non-abstract derived class.

21. Extension methods can not be applied to __________.

22. Which of the following statements is not true about extension methods?

23. The first parameter in an extension method must be preceded by the __________ keyword.

24. To write the code for a new interface in Visual Studio, first click __________ on the Visual Studio menu bar and then select Add New Item... .

25. An extension method can be added onto a class without __________ the class or inheriting from it.

26. It is recommended to put an extension method's class in its own __________.

27. An interface specifies __________ a class.

28. To declare an interface, use the __________ keyword.

29. When a class implements an interface, it __________.