Chapter 18 C Inheritance and Polymorphism n n

Chapter 18 C++ Inheritance and Polymorphism n n n By C. Shing ITEC Dept Radford University

Objectives n n n Understand how to create abstract class Understand how to use inheritance Understand how to use polyporphism 2

Inheritance n Inheritance tree n n n Parent: super-class (base class), larger set of objects, general functions Child: sub-class (derived class), subset of parent objects, special functions Parent class-child class relationship: child object “is a” parent object 3

Types of Inheritance 3 types of inheritance: n 1. 2. Public: derived class is public, most popular, used here every non-member class can access derived public functions Protected: derived classes are protected classes Only member function can access those functions Private: derived classes are private classes Only member function can access those functions 4

Public Inheritance Implementation Inheritance implementation Form: class child_class: public parent_class { Public: … Private: … } n 5

Inheritance Example Geometry Point 6

Inheritance Example (Cont. ) Point Circle Line Triangle Rectangle 7

Inheritance Example (Cont. ) Triangle Tetrahedran 8

Inheritance Example (Cont. ) Rectangle Parallelgram 9

Abstract Class n n The class includes only all specification No implementation 10

Abstract Class (Cont. ) n Example: Geometry class geometry. h 11

Inherited Class n Example: Point class point. h point. cpp 12

Inherited Class (Cont. ) n Example: Line class line. h line. cpp 13

Inherited Class (Cont. ) n Example: Triangle class triangle. h triangle. cpp 14

Inherited Class (Cont. ) n Example: Tetrahedran class tetrahedran. h tetrahedran. cpp 15

Inherited Class (Cont. ) n Example: Rectangle class rectangle. h rectangle. cpp 16

Inherited Class (Cont. ) n Example: Parallelgram class parallelgram. h parallelgram. cpp 17

Inherited Class (Cont. ) n Example: Circle class circle. h circle. cpp 18

Polymorphism n Decide data type of the class during run-time in inheritance tree. 19

Polymorphism (Cont. ) n Example: polymorphism. cpp 20

Polymorphism (Cont. ) n Example: whole program polymorphism_whole. cpp 21

References Deitel & Deitel: C How to Program, 4 th ed. , Chapter 19 & 20, Prentice Hall n 22