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Engineering Computer Science C++ How to Program (10th Edition)

To explain in what ways does polymorphism promotes extensibility. Polymorphism promotes extensibility: In C++, polymorphism enables the development of the same method name with different types and behaviors. For example, if circle, rectangle and square are required to be drawn and all these are the objects of the same base class shape having method draw, then draw must be the method with different behaviours for each one of them (circle, rectangle and square). Polymorphism makes use of two technologies: Virtual function Dynamic Binding Virtual function is a function that is declared in the base class and redefined in its derived classes. The keyword “virtual” precedes the function declaration in the base class. It instructs the compiler to include dynamic binding in the program. Dynamic binding is a concept in which the function definition is mapped at run time to the function call. Polymorphism is easy to extend the code by making all function calls generic. When a new class with the virtual function is added to the program, then no change is required in the generic function calls. Consider an example to illustrate how polymorphism promotes extensibility: Here, the class is Electronic which declares the virtual function create (). //include Header file #include<iostream> usingnamespacestd ; //base class with virtual function class Electronic { public: //denotes virtual function virtualvoidcreate() { cout <<"\n Member function of the base class..."; } } Class TV inherits class Electronic and redefines for function create(). class T : public Electronic { public: voidcreate() { cout <<"\n Virtual Member function of the derived class..."; } } The function main() instantiates the objects of the class and calls the create() function of both the classes. intmain() { //objects created Electronic *a,*b; a = newElectronic(); a→create(); b = newTV(); b→create(); } Now, another class Mobile is to be added which inherits the class Electronic. class Mobile: public Electronic { public: voidcreate() { cout <<"\n Virtual Member function of the derived class..."; } } The only modification is to be done in the main() function. intmain() { //objects created Electronic *a,*b,*c; a = newElectronic(); a→create(); b = newTV(); b→create(); c = newMobile(); c→create(); } Thus, polymorphism promotes extensibility.

To explain in what ways does polymorphism promotes extensibility. Polymorphism promotes extensibility: In C++, polymorphism enables the development of the same method name with different types and behaviors. For example, if circle, rectangle and square are required to be drawn and all these are the objects of the same base class shape having method draw, then draw must be the method with different behaviours for each one of them (circle, rectangle and square). Polymorphism makes use of two technologies: Virtual function Dynamic Binding Virtual function is a function that is declared in the base class and redefined in its derived classes. The keyword “virtual” precedes the function declaration in the base class. It instructs the compiler to include dynamic binding in the program. Dynamic binding is a concept in which the function definition is mapped at run time to the function call. Polymorphism is easy to extend the code by making all function calls generic. When a new class with the virtual function is added to the program, then no change is required in the generic function calls. Consider an example to illustrate how polymorphism promotes extensibility: Here, the class is Electronic which declares the virtual function create (). //include Header file #include<iostream> usingnamespacestd ; //base class with virtual function class Electronic { public: //denotes virtual function virtualvoidcreate() { cout <<"\n Member function of the base class..."; } } Class TV inherits class Electronic and redefines for function create(). class T : public Electronic { public: voidcreate() { cout <<"\n Virtual Member function of the derived class..."; } } The function main() instantiates the objects of the class and calls the create() function of both the classes. intmain() { //objects created Electronic a,b; a = newElectronic(); a→create(); b = newTV(); b→create(); } Now, another class Mobile is to be added which inherits the class Electronic. class Mobile: public Electronic { public: voidcreate() { cout <<"\n Virtual Member function of the derived class..."; } } The only modification is to be done in the main() function. intmain() { //objects created Electronic a,b,*c; a = newElectronic(); a→create(); b = newTV(); b→create(); c = newMobile(); c→create(); } Thus, polymorphism promotes extensibility.

Solution Summary: The author explains how polymorphism promotes extensibility by enabling the development of the same method name with different types and behaviors.

C++ How to Program (10th Edition)

C++ How to Program (10th Edition)

10th Edition

ISBN: 9780134448237

Author: Paul J. Deitel, Harvey Deitel

Publisher: PEARSON

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Chapter 12, Problem 12.8E

Chapter 12, Problem 12.10E

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Chapter 12 Solutions

C++ How to Program (10th Edition)

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