面向对象C习题参考解答

4-8 定义一个Dog类，包含age,weight等属性，以及对这些属性操作的方法。实现并测试这个类。#include using namespace std;class Dogpublic:void setAge(int a)age=a;int getAge()return age;void setWeight(float w)weight=w;float getWeight()return weight;private:int age;float weight;void main()Dog d;d.setAge(3);d.setWeight(30);cout小狗：d.getAge()岁，重d.getWeight()斤。endl;4-9 设计并测试一个名为Rectangle的矩形类，其属性为矩形的左下角与右上角两个点的坐标，根据坐标能计算矩形的面积。#include #include using namespace std;class Rectanglepublic:Rectangle(int xx1,int yy1,int xx2,int yy2)x1=xx1;y1=yy1;x2=xx2;y2=yy2;float getArea()return fabs(x2-x1)*fabs(y2-y1);private:int x1,y1;int x2,y2;void main()Rectangle rec(0,0,10,20);cout矩形面积：rec.getArea()endl;4-11 定义并实现一个矩形类，有长、宽两个属性，由成员函数计算矩形的面积。#include using namespace std;class Rectanglepublic:Rectangle(int l,int w)length=l;width=w;float getArea()return length*width;private:int length;int width;void main()Rectangle rec(10,20);cout矩形面积：rec.getArea()endl;4-13 定义一个Circle类，有数据成员radius（半径），成员函数getArea()，计算圆的面积，构造一个Circle的对象进行测试。#include using namespace std;const float PI=3.1415;class Circlepublic:Circle(float r)radius=r;float getArea()return radius*PI*PI;private:float radius;void main()Circle c(5.5);cout圆的面积：c.getArea()endl;4-20 定义一个复数类Complex，使得下面的代码能够工作。Complex c1(3,5);Complex c2=4.5;c1.add(c2);c1.show();/源程序如下：#include using namespace std;class Complexpublic:Complex(float r=0.0,float i=0.0)real=r;image=i;void add(Complex b)real=real+b.real;image=image+b.image;void show()coutreal+imageiendl;private:float real; /实部float image; /虚部;void main()Complex c1(3,5);Complex c2=4.5; /相当于Complex c2(4.5);c1.add(c2);c1.show();5-7 定义一个Cat类，拥有静态数据成员numOfCats,记录Cat的个体数目；静态成员函数getNumOfCats()，读取numOfCats。设计程序测试这个类，体会静态数据成员和静态成员函数的用法。#include using namespace std;class Catpublic:Cat()numOfCats+;Cat()numOfCats-;static int getNumOfCats()return numOfCats;private:static int numOfCats;int Cat:numOfCats=0;void main()cout现在的Cat数量：Cat:getNumOfCats()endl;Cat a;cout现在的Cat数量：a.getNumOfCats()endl;Cat b;cout现在的Cat数量：b.getNumOfCats()endl;5-14 定义Boat与Car两个类，二者都有weight属性，定义二者的一个友元函数getTotalWeight()，计算二者的重量和。#include using namespace std;class Car;class Boatpublic:Boat(float w)weight=w;friend float getTotalWeight(Boat b,Car c);private:float weight;class Carpublic:Car(float w)weight=w;friend float getTotalWeight(Boat b,Car c);private:float weight;float getTotalWeight(Boat b,Car c)return b.weight+c.weight;void main()Boat boat(3500);Car car(1000);cout船和汽车共重getTotalWeight(boat,car)公斤。endl;7-5 定义一个基类Shape，在此基础上派生出Rectangle和Circle，二者都有getArea()函数计算对象的面积。使用Rectangle类创建一个派生类Square。#include using namespace std;const float PI=3.14;class Shapepublic:Shape(float a,float b=0.0)this-a=a;this-b=b;protected:float a,b;class Rectangle : public Shapepublic:Rectangle(float l,float w):Shape(l,w)float getArea()return a*b;class Circle : public Shapepublic:Circle(float r):Shape(r)float getArea()return a*PI*PI;class Square : public Rectanglepublic:Square(float l):Rectangle(l,l)float getArea()return a*a;void main()Rectangle r(10,20);Circle c(5);Square s(10);cout矩形的面积：r.getArea()endl;cout圆的面积：c.getArea()endl;cout正方形的面积：s.getArea()endl;7-6 定义一个哺乳动物类Mammal，再由此派生出狗类Dog，定义一个Dog类的对象，观察基类与派生类的构造函数和析构函数的调用顺序。#include using namespace std;class Mammalpublic:Mammal()coutConstructing Mammal.endl;Mammal()coutDesstructing Mammal.endl;class Dog : public Mammalpublic:Dog()coutConstructing Dog.endl;Dog()coutDesstructing Dog.endl;void main()Dog d;7-8 定义一个Document类，有数据成员name，从Document派生出Book类，增加数据成员pageCount。#include using namespace std;class Documentpublic:Document(char * n)strcpy(name,n);void show()coutname;private:char name50;class Book : public Documentpublic:Book(char *n,int p):Document(n),pageCount(p)void show()cout书名：;Document:show();coutendl页数：pageCountendl;private:int pageCount;void main()Book book(C+语言程序设计,529);book.show();7-10 定义一个Object类，有数据成员weight及相应的操作函数，由此派生出Box类，增加数据成员height和width及相应的操作函数，声明一个Box对象，观察构造函数与析构函数的调用顺序。#include using namespace std;class Objectpublic:Object()coutConstructing Object.endl;Object()coutDestructing Object.endl;void setWeight(int w)weight=w;int getWeight()return weight;private:int weight;class Box : public Objectpublic:Box()coutConstructing Box.endl;Box()coutDestructing Box.endl;void setHeight(int h)height=h;int getHeight()return height;void setWidth(int w)width=w;int getWidth()return width;private:int height;int width;void main()Box box;box.setHeight(5);box.setWidth(10);box.setWeight(8);cout盒子：高box.getHeight()，宽box.getWidth()，重box.getWeight()endl;8-4#include using namespace std;class Counterpublic:Counter(int ii=0)i=ii;void print()couti=iendl;Counter operator +(int a)Counter temp;temp.i=i+a;return temp;private:int i;void main()Counter c;c=c+3;c.print();c=c+5;c.print();8-5#include using namespace std;class Mammalpublic:virtual void speak()coutMammal Speak!endl;class Dog:public Mammalpublic:virtual void speak()coutDog Speak!speak();8-7#include using namespace std;class Pointpublic:Point(int x=0,int y=0)X=x;Y=y;void print()cout(X,Y)endl;Point& operator+()X+;Y+;return *this;Point operator+(int)Point temp=*this;X+;Y+;return temp;private:int X,Y;void main()Point p;(+p).print();(p+).print();(+p).print();