面向?qū)ο驝++習(xí)題參考解答

4-8定義一個Dog類，包含age,weight等屬性，以及對這些屬性操作的方法。實現(xiàn)并測試這個類。#include<iostream>usingnamespacestd;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()<<"歲，重"<<d.getWeight()<<"斤。"<<endl;}4-9設(shè)計并測試一個名為Rectangle的矩形類，其屬性為矩形的左下角與右上角兩個點的坐標，根據(jù)坐標能計算矩形的面積。#include<iostream>#include<math.h>usingnamespacestd;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<<"矩形面積："<<rec.getArea()<<endl;}4-11定義并實現(xiàn)一個矩形類，有長、寬兩個屬性，由成員函數(shù)計算矩形的面積。#include<iostream>usingnamespacestd;classRectangle{public: Rectangle(intl,intw) { length=l; width=w; } floatgetArea() { returnlength*width; }private: intlength; intwidth;}; Cat() { numOfCats++; } ~Cat() { numOfCats--; } staticintgetNumOfCats() { returnnumOfCats; }private: staticintnumOfCats;};intCat::numOfCats=0;voidmain(){ cout<<"現(xiàn)在的Cat數(shù)量："<<Cat::getNumOfCats()<<endl; Cata; cout<<"現(xiàn)在的Cat數(shù)量："<<a.getNumOfCats()<<endl; Catb; cout<<"現(xiàn)在的Cat數(shù)量："<<b.getNumOfCats()<<endl;}5-14定義Boat與Car兩個類，二者都有weight屬性，定義二者的一個友元函數(shù)getTotalWeight()，計算二者的重量和。#include<iostream>usingnamespacestd;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<<"船和汽車共重"<<getTotalWeight(boat,car)<<"公斤。"<<endl;}7-5定義一個基類Shape，在此基礎(chǔ)上派生出Rectangle和Circle，二者都有g(shù)etArea()函數(shù)計算對象的面積。使用Rectangle類創(chuàng)建一個派生類Square。#include<iostream>usingnamespacestd;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<<"矩形的面積："<<r.getArea()<<endl; cout<<"圓的面積："<<c.getArea()<<endl; cout<<"正方形的面積："<<s.getArea()<<endl;}7-6定義一個哺乳動物類Mammal，再由此派生出狗類Dog，定義一個Dog類的對象，觀察基類與派生類的構(gòu)造函數(shù)和析構(gòu)函數(shù)的調(diào)用順序。#include<iostream>usingnamespacestd;classMammal{public: Mammal() { cout<<"ConstructingMammal."<<endl; } ~Mammal() { cout<<"DesstructingMammal."<<endl; }};classDog:publicMammal{public: Dog() { cout<<"ConstructingDog."<<endl; } ~Dog() { cout<<"DesstructingDog."<<endl; }};voidmain(){ Dogd;}7-8定義一個Document類，有數(shù)據(jù)成員name，從Document派生出Book類，增加數(shù)據(jù)成員pageCount。#include<iostream>usingnamespacestd;classDocument{public: Document(char*n) { strcpy(name,n); } voidshow() { cout<<name; }private: charname[50];};classBook:publicDocument{public: Book(char*n,intp):Document(n),pageCount(p) { } voidshow() { cout<<"書名："; Document::show(); cout<<endl<<"頁數(shù)："<<pageCount<<endl; }private: intpageCount;};voidmain(){ Bookbook("C++語言程序設(shè)計",529); book.show();}7-10定義一個Object類，有數(shù)據(jù)成員weight及相應(yīng)的操作函數(shù)，由此派生出Box類，增加數(shù)據(jù)成員height和width及相應(yīng)的操作函數(shù)，聲明一個Box對象，觀察構(gòu)造函數(shù)與析構(gòu)函數(shù)的調(diào)用順序。#include<iostream>usingnamespacestd;classObject{public: Object() { cout<<"ConstructingObject."<<endl; } ~Object() { cout<<"DestructingObject."<<endl; } voidsetWeight(intw) { weight=w; } intgetWeight() { returnweight; }private: intweight;};classBox:publicObject{public: Box() { cout<<"ConstructingBox."<<endl; } ~Box() { cout<<"DestructingBox."<<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()<<"，寬"<<box.getWidth()<<"，重"<<box.getWeight()<<endl;}8-4#include<iostream>usingnamespacestd;classCounter{public: Counter(intii=0) { i=ii; } voidprint() { cout<<"i="<<i<<endl; } Counteroperator+(inta) { Countertemp; temp.i=i+a; returntemp; }private: inti;};voidmain(){ Counterc; c=c+3; c.print(); c=c+5; c.print();}8-5#include<iostream>usingnamespacestd;classMammal{public: virtualvoidspeak() { cout<<"MammalSpeak!"<<endl; }};classDog:publicMammal{public: virtualvoidspeak() { cout<<"DogSpeak!"<<endl; }};voidmain(){ Dogd; d.speak(); Mammal*p=&d; p->speak();}8-7#include<iostream>usingnamespacestd;classPoint{public: Point(intx=0,inty=0) { X=x; Y=y; } void