Chapter 18 C Inheritance and Polymorphism

1
Chapter 18 C Inheritance and Polymorphism

• By C. Shing
• ITEC Dept
• Radford University

2
Objectives

• Understand how to create abstract class
• Understand how to use inheritance
• Understand how to use polyporphism

3
Inheritance

• Inheritance tree
• 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

4
Types of Inheritance

• 3 types of inheritance
• 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

5
Public Inheritance Implementation

• Inheritance implementation
• Form
• class child_class public parent_class
• Public
• Private

6
Inheritance Example
7
Inheritance Example (Cont.)
Circle
8
Inheritance Example (Cont.)
9
Inheritance Example (Cont.)
10
Abstract Class

• The class includes only all specification
• No implementation

11
Abstract Class (Cont.)

• Example Geometry class
• geometry.h

12
Inherited Class

• Example Point class
• point.h
• point.cpp

13
Inherited Class (Cont.)

• Example Line class
• line.h
• line.cpp

14
Inherited Class (Cont.)

• Example Triangle class
• triangle.h
• triangle.cpp

15
Inherited Class (Cont.)

• Example Tetrahedran class
• tetrahedran.h
• tetrahedran.cpp

16
Inherited Class (Cont.)

• Example Rectangle class
• rectangle.h
• rectangle.cpp

17
Inherited Class (Cont.)

• Example Parallelgram class
• parallelgram.h
• parallelgram.cpp

18
Inherited Class (Cont.)

• Example Circle class
• circle.h
• circle.cpp

19
Polymorphism

• Decide data type of the class during run-time
• in inheritance tree.

20
Polymorphism (Cont.)

• Example
• polymorphism.cpp

21
Polymorphism (Cont.)

• Example whole program
• polymorphism_whole.cpp

22
References

• Deitel Deitel C How to Program, 4th ed.,
• Chapter 19 20, Prentice Hall