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

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 . < 1.1?:；:->：.； , 7 : ； ?：</, ， ., * ， . * ； ：；static intnumber; ：； ？：'.：；，；,、：.：double xCooriyCoord; 5 / :可二：；.；：.:；Shapc(0llbIe x,double y):xCoord(x),yCoord(y) .， _ *, ,' Z 'a . , , ifcout«,Shape,s constructor0 << endi; I -；: < virtual double AreaQ const ; ；： .； .三;1.；. ；：.：I ,、, , , . » . 、. > / , . , .» , , . ,* / ' V-： 1 coin<< "Shape's area is" .： ” ：；、;；：return 0.0;, J 、 ' . :* , . / :. , .: . j. , , a ' '» (' a ( , ZHShapeO ， . H .:. , ' . z , ,：.cout"Shape's destructor*« endl; ：； : .工 . * * *manager. calculatePayment();salesperson. calculatePayment();employee, demote();return 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 represent 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 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 of 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 pointer 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 toStringQ 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 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 the 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 <iostream> using namespace std;class Person protected:string name;string address;public:Person(string name = 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 () 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, Square 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 <iostream>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 : public 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 private: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) 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 = << triangle. 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 has 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 i on and a top-1 eve I funct i on with a pointer to cI ass Shape.cpp#include<iostream> 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 ThreeDShape : 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 area() /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class 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. << endl;float volume () 计算球体的体积上述代码中，每个类都继承自其对应的父类，并实现了虚拟函数。基类'Shape'中定义 了纯虚拟函数'print' ,而'TwoDShape'和'ThreeDShape'分别定义了纯虚拟函数'area'、 perimeter'volume' o子类 Triangle'、'Square'和 Circle'继承自 TwoDShape',分别 实现了面积和周长的计算方法;子类 Cube'、' Cylinder'和' Sphere'继承自ThreeDShape' , 分别实现了体积的计算方法。class Circle:public Shapepublic:Circle(double x,double y):Shape(x,y)( . cout« ”Circle's constructor11« cndl;. . number i-b;virtual double Area。const : ：. .:cout«/'Circled area isw;.return 3.14*xCoord*xCoord; 一 Circled., , . . . , , , a a , * * «« , , . .cou(« "Circle's destructor" vv endl; .'': J -:；：" ：一class Rcctangle;public Shape , , , , > : .， public:,.Rectangle(doublc x.double y):Shape(x5y)一:cout«,rRectanglers constructor1' « endl; numberH",J.-virtual double Area。const .cout«'Rectangle's 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-. - . / '' . -. , . , , . 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 . , . . . , , . , .:'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 * e , , , . . . . .K., ._. , , , .：cout« ”i from B is ：'«i << etidl;: . , , , . . . , . . . . . . . , . . . . . J virtual void sefl(int m)：】 : cout «”Set a value in Class Bn h;：；：1 3 * m; .：； . * . ： 、. ; ,intmainO . . ' / . . . . > . . , , , , . . , . .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 int 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"：！：；：；：,* * . * * * * * * * * , 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, department 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) Display the i nformat i on for cI asses Student and Teacher.、 、 、cppttinclude <iostream> ttinclude <string>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 : public 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；class 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 calculateWorkTime() 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 () <<