第04讲类和对象程序设计实习

第三讲类和对象 2doublereal,Complex(inti) cout<<"IntConstructorcalled"<<endl;real=i;imag=0;real=r;imag= intmainComplexc1(7,8);Complexc2=c1 3}cout<<c1.real<<""<<3}析构函数析构函数面加4classprivatechar*p;CString()p=new}~CString()CString::~{delete[]}5classCtest{~Ctest(){cout<<"destructorcalled"<<endl;intmain()Ctestcout<<"EndMain"<<endl;return0;}

EndMain6析构函数和运算符deletepTest=newpTest=new Test=newCtestdelete[]7~CMyclass(){cout~CMyclass(){cout<<"destructor"<<endl;returnsobj; }intreturnsobj; }intobj=fun(obj);//函数调用的返回值（临时对象）被return0; }

9classDemointid;Demo(int{id=printf("id=%d,Construct\n",}{printf("id=%d,Destruct\n",}voidstaticvoidstaticDemoDemod33printf("fun\n");}intmainDemod4printf("main\n");Demod5 rintf"endmain\n");return0;} #include<iostream>using CMyclass(){};CMyclass(CMyclass&c)coutcout<<"copyconstructor"<<}~CMyclass(){cout<<"destructor"<<endl;}CMclassccout<<"test"}CMclassccout<<"test"<<}copy intcopydestructor//返回值临时对象消亡 //局部变量消亡 //全局变量消亡}class Vs.

intw,h;staticintCRectangle(intw_,intstaticvoid

可以通过：

CRectangle*p=&r; .CRectangle&refintn=上面这三种方式效果和类名::成员名没区别静态成员变量不classCMyclass{intn;staticintsizeof(CMyclass class{staticintnTotalArea;staticintnTotalArea;CRectanleintw_,intstaticvoid{w=w_;h=h_;nTotalNumber++;nTotalArea+=w*h;{nTotalNumber--;nTotalArea-=w*h;}voidcoutcout<<nTotalNumber<<","<<nTotalArea<<}intCRectanle::nTotalArea=0 int{CRectangler1(3,3),}void{cout<<w<<","<<nTotalNumber<<","<<nTotalArea<<endl;//wrongCRectangler;CRectangler;class{staticintnTotalArea;staticintnTotalArea;CRectangle(intw_,intstaticvoidCRectangle nTotalNumbernTotalArea的值 构造函CRectangle::CRectangle(CRectangle&r){w=r.w; h=r.h;nTotalNumber++;nTotalArea+=w*h;}◼◼

构造函数(调用方式Complexc1,c2(2),Complex*pc1=newComplex;ComplexComplex*pc1=newComplex;Complex*pc2=newComplex(3,4)；Testarray1[3]={1,Test(1,2)Test*pArray[3]={newTest(4),newTest(1,2)构造函数 Complex Complexc2= 析构函数(定义~类名(){析造函数(调用时机全局变量函数中静态变量函数中静态变量函数参数函数中变量函数返回值全局变量函数中静态变量 函数中静态变量C++的标准int#include<iostream>usingintA(intx_):x(x_)cout<<x<<"constructorcalled"<<}~A(){cout<<x<<"destructorcalled"<<endl;intmain()}2constructor2constructor2destructorclassA intintA(intx_):x(x_)cout<<x<<"constructorcalled"<<}

Aa=f();return0;}A(constA&a//本例中dev需要此const其他编译器不要x=2+a.x;cout<<"copycalled"<<}

~A(){cout<<x<<"destructorcalled"<<endl;AAf(return

1constructorcalledcopycalled12destructor12destructor12destructor10destructor intmain()intA(intx_):x(x_)cout<<x<<"constructorcalled"<<

Aa=f();return0;}A(constA&a){x=2+a.x;cout<<"copycalled"<<

}~A(){cout<<x<<"destructorcalled"<<endl;Af(Areturn}

1constructor10destructor

conststringSCHOOL_NAME=“Pekingintn,constint*p=&*p=5;//编译出错n=4; p=&m;constconstint*p1;int*p2;1= 2;//okp2=p1;p2=(int*)p1; voidMyPrintf(constchar*p{ this//编译出错cout<<p;//ok}intintconstint&r=n;r=5;//errorn=4;前面加const关键字classSample}constSampleObj; (静态成员函数除外)public:intvoidpublic:intvoidGetValue()voidfunc(){}intvalue=0;}intconstSample//VisualStudio2010//VisualStudio2010中没有问题，在DevC++中，要为Sample类编写无 classSamplevoidGetValue()voidGetValue()voidSample::GetValue()const cout<<}constT&voidPrintfObj(constSample&o{ o.GetValue();//okSample&r=(Sample&)o;//必须强制类型转换 }int

CTest(){n=1;intmain()intGetValue()const{returnnintmain()CTestobjTest2;objTest2.GetValue();}

","输出结果:1,

intintintCTyre(intr,intw:radiusr,width{classCCar{//汽车类intprice;//价格CTyretyre;CCar(intp,inttr,inttw{}}int{CCarcar;//compile{),{…}函数/变量 表达式中的函数,变量有定 classCTyre{CTyre(){cout<<"CTyrecontructor"<<endl;~CTyre(){cout<<"CTyredestructor"<<endl;CEngine(){cout<<CEngine(){cout<<"CEnginecontructor"<<endl;~CEngine(){cout<<"CEnginedestructor"<<endl;classCCar{CTyretyre;CCar(){cout<<"CCarcontructor"<<endl;~CCar(){cout<<"CCardestructor"<<endl;CCarcar;return0;}intCCarcar;return0;}CEnginecontructorCTyrecontructorCCarcontructorCCardestructorCTyredestructorCEnginedestructor →它里面包 对，也会A(){cout<<“default”<<endl;}A(A&a){cout<<"copy"<<endl;}

classB{Aa;};intmain(){Bb1,

而调 } 初始化const成员 intclassCDemoconstintconstintnum//

int& int cout<<sizeof(CDemo)cout<<sizeof(CDemo)<<endl;return0;//输出结果是友元 classCCar;//提 classintfriendintMostExpensiveCarCCarcars[],inttotal); friendvoidCDriver::ModifyCar(CCar* }inttmpMax=-for(inti=0;i<total;++i}int}int{}classB 一类的成员函数(classBvoidclassAfriendvoidclassclassintfriendclass CCarvoidModifyCar(){// intint return thisclassCCar{int

structintprice=p;voidSetPrice(CCar*this,int}}intmain(){CCarc