C++面向对象程序设计双语教程（第3版）-参考答案【ch07】Polymorphism and Virtual Functions.docx

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1、Chapter 7 PoIymorph i sm and Vi rtuaIFunct i ons1. Wr ite the output of the fol lowing program.class Shape public:v 7. v . ：.； , 7 : ； ?：/, ， ., * ， . * ； ：；static intnumber; ：； ？：.：；，；,、：.：double xCooriyCoord; 5 / :可二：；.；：.:；Shapc(0llbIe x,double y):xCoord(x),yCoord(y) .， _ *, , Z a . , , ifcout,Sh

2、ape,s constructor0 endi; I -；: / , . , . , , . ,* / V-： 1 coin Shapes area is; .： ” ：；、;；：return 0.0;, J 、 . :* , . / :. , .: . j. , , a ( a ( , ZHShapeO ， . H .:. , . z , ,：.coutShapes destructor* endl; ：； : .工 . * * *manager. calculatePayment();salesperson. calculatePayment();employee, demote();re

3、turn 0;这段代码定义了一个基类Employee,以及从该类派生的Manager和Salesperson类。 Employee类有级别、工资和工作时间的成员变量，以及计算支付和降级的成员函数。Manager 类还有一个雇主成员变量，并重写了计算支付的函数。Salesperson类还有销售额成员变量, 并也重写了计算支付的函数。在主函数中，示例了如何创建员工、经理和销售员对象，并调用它们的计算支付函数和 降级函数。输出会显示出每个类的支付金额，以及员工降级后的级别。6. Here i s a c I ass h i erarchy, shown i n Figure 7-5, to repr

4、esent var i ous med i a objects:G i ven the def i n i t i on of the base cI ass Med i a:class Media . . : . . . . s *.1 * , , .r*- . . .- ，.:；：加谖泊.M丽阳等蕊举M二 virtual void priirtO = 0; . , , * /f . s * , . a . . ,三;：virtual string id。三0; 三三, protected： ”m string t /. . . . .：； .*, .懑涔涔犊哨案第海浅落澎 .Figure

5、7-5 The hierarchy diagram of these media objects(1) Exp lain the cI ass re I at i onsh i p descr i bed i n the h i erarchy d i agram.(2) Def i ne the Book and Magaz i ne cI asses accord i ng to the h i erarchy d i agram. (Hint: The pr i nt funct i on of each cI ass d i spI ays a I I i nformat i on o

6、f data members. The i d funct i on of each cI ass returns a str i ng i dent i f i er that can i nd i cate the med i a feature. Th i s i dent i f i er cons i sts of data members of each cI ass)(3) Wr i te the ma i n funct i on to test the Book and Magaz i ne c I asses. (Hint: You must def ine a point

7、er to a Media object in the main function.)略。7. Des i gns a cI ass named Person and i ts der i ved cI asses named Student and EmpIoyee.Assume that the dec Iarat ion of the Person cI ass i s as fol lows:class Person public:Pcrson(string stfN, string strA): name(strN)? address(strA)virtual string toSt

8、ringQ const;private:string name, address; / 9.一：J ；二：.：:, z -(1) Def i ne the toStr i ng funct i on i n the Person cI ass. The return i ng va I ue of the toStr i ng funct i on i s used to display the cI ass i nformat i on in the fol lowing format: Name: XXXX;Address: XXXXXXX.(2) Def i ne the Student

9、 cI ass der i ved from the Person cI ass. A student has a cI ass status (freshmen, sophomore, jun i or, or sen i or). Overr i de the toStr i ng funct i on i n the Student cI ass.(3) Def i ne the EmpIoyee cI ass der i ved from the Person cI ass. An empIoyee has an off i ce and a saI ary. Overr i de t

10、he toStr i ng funct i on i n the EmpIoyee cI ass.(4) Write a top I eve I funct i on with a parameter of Person type and wr i te the ma i n funct i on to test the Student and EmpIoyee cI asses.epp ttinclude using namespace std;class Person protected:string name;string address;public:Person(string nam

11、e = string address = this-name = name;this-address 二 address;string toStringO return Name: + name + ; 地址： + address + )；class Student : public Person private:int studentID;public:Student(string name = string address = int studentID = 0) :Person(name, address) this-studentID = studentID;)；int main ()

12、 Person person(John 123 Main St Student student(Alice 456 Elm St 12345);cout Person: endl;cout person. toStringO endl;cout Student: endl;cout student. toStringO endl;return 0;这段代码定义了一个名为Person、的基类及其名为Student的派生类。Person类有一 个toString函数，用于返回格式化的类信息。Student类从Person类派生而来，并添加了 一个名为studentID的新成员。在主函数中，我们创建

13、了一个Person对象和一个Student对象，并分别输出它们的类 信息。运行该程序，你将得到类似以下的输出结果：Person:Name: John;地址：123 Main St.Student:Name: Alice;地址:456 Elm St.Wr ite a program.1712 3z(x /( z(Abstract base cI ass Shape.Classes Tr iangle, Square and Circle are der i ved from Shape.CaIcuI ate the areas and per imeters of Tr iangle, Squa

14、re and Circle.下面是一个使用C+编写的示例程序，实现了抽象基类Shape和派生类Triangle、Square 和Circle的功能。每个形状类都可以计算自身的面积和周长。请注意，代码中的计算公式 可能需要根据实际情况进行更改。、CPPttinclude using namespace std;/抽象的基类形状class Shape public:/纯虚函数，用于计算面积virtual float getAreaO = 0;/纯虚函数，用于计算周长virtual float getPerimeter()二 0;)；/类三角形，从形状派生class Triangle : publi

15、c Shape private:float base;float height;public:/构造函数Triangle(float base, float height) this-base = base;this-height = height;/重写计算面积的函数float getArea() override return 0. 5 * base * height;/重写计算周长的函数float getPerimeter() override /假设三角形的边长相等return 3 * base;)；/类方形，从形状派生class Square : public Shape priva

16、te:float side;public:/构造函数Square(float side) this-side = side;)/重写计算面积的函数float getAreaO override return side * side;/重写计算周长的函数float getPerimeter () return 4 * side;)；/类圆形，从形状派生class Circle : public Shape private:float radius;const float pi = 3. 14159; / 假设圆周率为 3. 14159public:/构造函数Circle(float radius

17、) this-radius radius;)/重写计算面积的函数 float getAreaO override return pi * radius * radius;/重写计算周长的函数float getPerimeter() override return 2 * pi * radius;)；int main() /创建三个形状对象Triangle triangle(5, 8);Square square(4);Circle circle(3);/输出每个形状的面积和周长cout Triangle: Area = triangle. getAreaO Perimeter = triang

18、le. getPerimeter () endl;cout Square: Area = square. getAreaO Perimeter = square. getPerimeter () endl;cout Circle: Area = circle. getAreaO Perimeter = circle. getPerimeter () endl;return 0;这个程序定义了一个抽象基类Shape,以及派生类Triangle、Square和Circle。每个 派生类实现了 Shape基类中的纯虚函数getAreaO和getPerimeter (),并提供了自己的实 现。在主函数

19、中，我们创建了一个Triangle对象、一个Square对象和一个Circle对象， 并使用它们的成员函数分别计算和输出面积和周长。9. Design a cI ass h i erarchy as foI Iows;(1) A base cI ass Shape with v i rtuaI funct i on print.(2) CI asses TwoDShape and ThreeDShape der i ved from Shape. T i voDShape has v i rtuaI funct i ons area and per imeter: ThreeDShape ha

20、s v i rtuaI funct i on voIume.(3) CI asses Tr i angIe, Square and Circle are der i ved from TwoDShape.(4) Classes Cube, Cuboid and Sphere are der i ved from ThreeDShape.Overr i de the def i n i t i on of the print funct i on of each der i ved cI ass. Test the h i erarchy by us i ng the ma i n funct

21、i on and a top-1 eve I funct i on with a pointer to cI ass Shape.cpp#include using namespace std;/基类形状class Shape public:virtual void print() = 0; / 虚拟函数打印 )；/二维形状类class TwoDShape : public Shape public:virtual float area()=0; /虚拟函数计算面积virtual float perimeter() = 0; / 虚拟函数计算周长 ；/三维形状类class ThreeDShap

22、e : public Shape public:virtual float volume() = 0; / 虚拟函数计算体积 )；/三角形类class Triangle : public TwoDShape public:void print () cout This is a triangle. endl; float area() /计算三角形的面积)float perimeter() /计算三角形的周长)；/方形类class Square : public TwoDShape public:void print () cout This is a square. endl;float a

23、rea() /计算方形的面积)float perimeter() /计算方形的周长)；/圆形类class Circle : public TwoDShape public:void print () cout This is a circle. endl;)float area () /计算圆形的面积)float perimeter () /计算圆形的周长)；/立方体类class Cube : public ThreeDShape public:void print () cout This is a cube. endl;)float volume () /计算立方体的体积)；/圆柱体类cl

24、ass Cylinder : public ThreeDShape public:void print () cout This is a cylinder. endl;float volume () /计算圆柱体的体积)；/球体类class Sphere : public ThreeDShape public:void print () cout This is a sphere. : .， public:,.Rectangle(doublc x.double y):Shape(x5y)一:cout,rRectanglers constructor1 endl; numberH;,J.-vi

25、rtual double Area。const .coutRectangles area is”；return xCoord*yCoord;) . , ：/Rectangle() ， . . . , ,cout ”Rectangles destructor*1 endl;： ：； ：. :二.；. .：3.；：；： ： . .-void fun(const Shape &sp) ,二.X. . . e , :, , ., . .,.：cout sp AreaQ endl;. int Shape: znumber 0;：、 . , . ., in TRsi)0-. - . / . -. , .

26、, , . C. . . ;：. Circle c(2.0,5.0);.Rectangle r(2.0,4.0);cout c.mmiber endl;. cout r.number eadl; 一 ；:： 二二：丁.二： ；：二；二: ： m；.：,：；：.丁丁：3 ；：.：.三二二:工工，二一 略。2. Wr ite the output of the fol lowing program.classA:二P同c: .aa ，；AU . :. . , _ . . . 9 . ： cout vi from A is ” i endl; ;：* * J . , . . . , , . , .:

27、七二；.；.；三：上：. ；：.；void tn-. . z .： /.； sctI(20); 旌 * * * * * * * * * * * , , . , , . , , fvirtual void setl(int m), tout Set a value in Class An *;i = 2 Am； . , . . , . * *jwotected:：.inti;-.);二二二二一,二： , . class B: public A ; , .* * j e , * , .：. ,. , , ,., , . . 一 _ _ . public: , * . * . , , * , J *

28、 e , , , . . . . .K., ._. , , , .：cout ”i from B is ：i . . , , , , . . , . .A* new BO； , . , , , , r , ., . 、Z： ；. ：. ? ： . /.：.z/. 略。3. G i ven the def i n i t i on of a Person cI ass as foI Iows:class Person=;。匚;mm-Hm七;tpublic:. ,. Jt , . . . - . . : , Person(sttingn; inti):name(n), id(i)virtual i

29、nt Tnne0 = 0；/A person spends time doing something.virtual void print。 cout name id endl; pnvate:二:：:二；.三,士二;丫；：；：三，二：,上：w.,：二 w:二 m二：，.：.：二；,二：二：匚：.：;二：.；：.：;：三；：二二;：彳上；：；.string name;int id;:二:二七三：-二 m；：；.：.,：.： ： :；： ；，；丁：八：.： J：.；:二：/；二：).：“： ：.：,.： ；：/*：； ：:二：3：，；:：，；一：.：，：；：:：；：二：！：；：；：,* * .

30、* * * * * * * * , J * a * * * * , , , , , ( * * ；： * * * * . , * * _ , J9 .Des i gn the two c I asses Student and Teacher. They are der i ved from c I ass Person.(1) CI ass Student has the propert i es of name, i d, cIassNo and studyT ime per week;CI ass Teacher has the propert i es of name, i d, de

31、partment and workT ime per week.(2) CaIcuI ate the work/student time. CaIcuI at i ng methods are def i ned as fol lows:The study time of a student i s the c I ass quantity multipl ied by 2 (hour) per week;The work time of a teacher i s the teach i ng quant i ty mu 11 i p I ied 2 (hour) per week.(3)

32、Display the i nformat i on for cI asses Student and Teacher.、 、 、cppttinclude ttinclude using namespace std;class Person protected:string name;long id;public:Person (string name, long id) : name( name), id (_id) string getName() const return name; long getld() const return id; ；class Student : publi

33、c Person private:string className;int studyTime;public:Student (string _name, long _id, string _className, int _studyTime) :Person( name, _id), className(_className), studyTime(_studyTime) ()int getStudyTime() const return studyTime; int calculateWorkTime() const return studyTime * 2; 计算学生的学 习时间；cla

34、ss Teacher : public Person private:string department;int teachingQuantity;public:Teacher(string name, long _id, string department, int _teachingQuantity):Person(_name,_id),department(_department),teachingQuantity QteachingQuantity) int getTeachingQuantity() const return teachingQuantity; int calcula

35、teWorkTime() const return teachingQuantity * 2; / 计算 教师的工作时间)；int main () /创建学生对象Student student (、张三 1234567890, 三年级一班 10);/创建教师对象Teacher teacher (、李四、9876543210, 数学系、5);/输出学生和教师的信息cout 学生姓名： student. getNameO endl;cout 学生身份证: student, getld () endl;cout 、学生班级： student. getClassName () endl;cout 学生

36、学习时间： student. getStudyTime () 小时/周、 endl;cout 学生工作时间: student. calculateWorkTime () 小时/周 endl;cout endl;cout 、教师姓名: teacher. getName () endl;cout 教师身份证: teacher, getld () endl;cout 、教师部门： teacher. getDepartment () endl;cout 教师教学数量： teacher. getTeachingQuantity () 节/周 endl;cout 教师工作时间: teacher. calculateWorkTime ()