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。#includeiostreamusingnamespacestd;classDog{public:voidsetAge(inta){age=a;}intgetAge(){returnage;}voidsetWeight(floatw){weight=w;}floatgetWeight(){returnweight;}private:intage;floatweight;};voidmain(){Dogd;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。#includeiostream#includemath.husingnamespacestd;classRectangle{public:Rectangle(intxx1,intyy1,intxx2,intyy2){x1=xx1;y1=yy1;x2=xx2;y2=yy2;}floatgetArea(){returnfabs(x2-x1)*fabs(y2-y1);}private:intx1,y1;intx2,y2;};voidmain(){Rectanglerec(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。#includeiostreamusingnamespacestd;classRectangle{public:Rectangle(intl,intw){length=l;width=w;}floatgetArea(){returnlength*width;}private:intlength;intwidth;};voidmain(){Rectanglerec(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。#includeiostreamusingnamespacestd;constfloatPI=3.1415;classCircle{public:Circle(floatr){radius=r;}floatgetArea(){returnradius*PI*PI;}private:floatradius;};voidmain(){Circlec(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。Complexc1(3,5);Complexc2=4.5;c1.add(c2);c1.show();//源程序如下：#includeiostreamusingnamespacestd;classComplex{public:Complex(floatr=0.0,floati=0.0){real=r;image=i;}voidadd(Complexb){real=real+b.real;image=image+b.image;}voidshow(){coutreal+imageiendl;}private:floatreal;//实部floatimage;//虚部};voidmain(){Complexc1(3,5);Complexc2=4.5;//相当于Complexc2(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。#includeiostreamusingnamespacestd;classCat{public:Cat(){numOfCats++;}~Cat(){numOfCats--;}staticintgetNumOfCats(){returnnumOfCats;}private:staticintnumOfCats;};intCat::numOfCats=0;voidmain(){cout现在的Cat数量：Cat::getNumOfCats()endl;Cata;cout现在的Cat数量：a.getNumOfCats()endl;Catb;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。#includeiostreamusingnamespacestd;classCar;classBoat{public:Boat(floatw){weight=w;}friendfloatgetTotalWeight(Boatb,Carc);private:floatweight;};classCar{public:Car(floatw){weight=w;}friendfloatgetTotalWeight(Boatb,Carc);private:floatweight;};floatgetTotalWeight(Boatb,Carc){returnb.weight+c.weight;}voidmain(){Boatboat(3500);Carcar(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。#includeiostreamusingnamespacestd;constfloatPI=3.14;classShape{public:Shape(floata,floatb=0.0){this-a=a;this-b=b;}protected:floata,b;};classRectangle:publicShape{public:Rectangle(floatl,floatw):Shape(l,w){}floatgetArea(){returna*b;}};classCircle:publicShape{public:Circle(floatr):Shape(r){}floatgetArea(){returna*PI*PI;}};classSquare:publicRectangle{public:Square(floatl):Rectangle(l,l){}floatgetArea(){returna*a;}};voidmain(){Rectangler(10,20);Circlec(5);Squares(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。#includeiostreamusingnamespacestd;classMammal{public:Mammal(){coutConstructingMammal.endl;}~Mammal(){coutDesstructingMammal.endl;}};classDog:publicMammal{public:Dog(){coutConstructingDog.endl;}~Dog(){coutDesstructingDog.endl;}};voidmain(){Dogd;}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。#includeiostreamusingnamespacestd;classDocument{public:Document(char*n){strcpy(name,n);}voidshow(){coutname;}private:charname[50];};classBook:publicDocument{public:Book(char*n,intp):Document(n),pageCount(p){}voidshow(){cout书名：;Document::show();coutendl页数：pageCountendl;}private:intpageCount;};voidmain(){Bookbook(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。#includeiostreamusingnamespacestd;classObject{public:Object(){coutConstructingObject.endl;}~Object(){coutDestructingObject.endl;}voidsetWeight(intw){weight=w;}intgetWeight(){returnweight;}private:intweight;};classBox:publicObject{public:Box(){coutConstructingBox.endl;}~Box(){coutDestructingBox.endl;}voidsetHeight(inth){height=h;}intgetHeight(){returnheight;}voidsetWidth(intw){width=w;}intgetWidth(){returnwidth;}private:intheight;intwidth;};voidmain(){Boxbox;box.setHeight(5);box.setWidth(10);box.setWeight(8);cout盒子：高box.getHeight()，宽box.getWidth()，重box.getWeight()endl;}8-4#includeiostreamusingnamespacestd;classCounter{public:Counter(intii=0){i=ii;}voidprint(){couti=iendl;}Counteroperator+(inta){Countertemp;temp.i=i+a;returntemp;}private:inti;};voidmain(){Counterc;c=c+3;c.print();c=c+5;c.print();}8-5#includeiostreamusingnamespacestd;classMammal{public:virtualvoidspeak(){coutMammalSpeak!endl;}};classDog:publicMa