Chapter_12

Base class
Student Shape Loan Employee Account
Derived classes
GraduateStudent, UndergraduateStudent Circle, Triangle, Rectangle, Sphere, Cube CarLoan, HomeImprovementLoan, MortgageLoan Faculty, Staff CheckingAccount, SavingsAccount
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// Fig. 12.4: CommissionEmployee.h // CommissionEmployee class definition represents a commission employee. #ifndef COMMISSION_H #define COMMISSION_H #include <string> // C++ standard string class using std::string; class CommissionEmployee { public: CommissionEmployee( const string &, const string &, const string &, double = 0.0, double = 0.0 ); void setFirstName( const string & ); // set first name string getFirstName() const; // return first name void setLastName( const string & ); // set last name string getLastName() const; // return last name void setSocialSecurityNumber( const string & ); // set SSN string getSocialSecurityNumber() const; // return SSN void setGrossSales( double ); // set gross sales amount double getGrossSales() const; // return gross sales amount void setCommissionRate( double ); // set commission rate (percentage) double Henan University of 2013-7-29 getCommissionRate() const; // return commission rate Technology 15
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12.1 12.2 12.3 12.4
Introduction Base Classes and Derived Classes protected Members Relationship between Base Classes and Derived Classes 12.4.1 Creating and Using a CommissionEmployee Class 12.4.2 Creating a BasePlusCommissionEmployee Class Without Using Inheritance 12.4.3 Creating a CommissionEmployee-BasePlusCommissionEmployee Inheritance Hierarchy 12.4.4 CommissionEmployee-BasePlusCommissionEmployee Inheritance Hierarchy Using protected Data
A class is derived from multiple base class
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Indirect base class


Single inheritance


Multiple inheritance

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2.Three Kinds Of Inheritance
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12.4.1 The 1th example


Creating and Using a CommissionEmployee Class P412
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Each arrow represents Inheritance relationships the “is-a” relationship
form treelike hierarchy structures. A class becomes either a base class ---supplying members to other class, a derived class---- inheriting its members from other classes, or both.
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Object-Oriented Programming: Inheritance
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OBJECTIVES
In this chapter you will learn: To create classes by inheriting from existing classes. How inheritance promotes software reuse. The notions of base classes and derived classes and the relationships between them. The protected member access specifier. The use of constructors and destructors in inheritance hierarchies. The differences between public, protected and private inheritance. The use of inheritance to customize existing software.

The has-a relationship represents composition.

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12.2 Base Classes and Derived Classes

One base class can have many derived class.
2006 Pearson Education, Inc. All rights reserved.
12.1 Introduction


Inheritance is a form of software reuse in which the programmer creates a class that absorbs an existing class’s data and behaviors and enhances them with new capabilities. The existing class is called the base class (superclass), the new class is called derived class (subclass ).
Fig. 12.2 | Inheritance hierarchy for university CommunityMembers.
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Fig. 12.3 | Inheritance hierarchy for Shapes. Class TwoDimensionalShape : public Shape
Public inheritance
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Public Inheritance



With all forms of inheritance, private members of a base class are not accessible from that class’s derived class, but these private members are still inherited. With public inheritance, all other base-class members retain their original member access when they become members of the derived class. Friend functions are not inherited.