1313040实验六：继承与派生

实验六继承和派生姓名:学号成绩评语：实验目的掌握单继承和多重继承下派生类的定义方法理解基类成员在不同的继承方式下不同的访问属性正确定义派生类的构造函数与析构函数，理解定义一些个派生类对象时各个构造函数、析构函数被调用的顺序；学习利用虚基类解决二义性问题。实验任务1.定义一个车基类vehicle，派生出自行车类bicycle和汽车类car，又以自行车和汽车类为基类共同派生出摩托车类motorcycle，每个类都要定义带参数的构造函数。对自行车类继承车基类的方式分别用private,protected,public，观察基类成员在派生类中的访问属性；观察自行车类、汽车类和摩托类对象定义时构造、析构函数的调用顺序。具体完成以下要求：（1）定义基类vehicle，具有两个保护成员变量：maxspeed,weight，有3个公有的成员函数：run(),stop,show()，以及带参数的构造函数、析构函数；再定义一个从vehicle公有继承的bicycle类，增加height保护属性的成员变量，定义bicycle类的构造函数、析构函数，改选show()函数，用于输出本类中的完整信息。Main()函数中定义bicycle类对象，观察构造函数和析构函数的执行顺序，以及各成员函数的调用。请用跟踪的方法观察程序运行的每一步究竟调用的是哪一个函数。（2）在上一步的基础上，将继承方式分别修改为protected和private，再重新编译，观察这时的报错信息并能解释。修改程序使程序正确运行。（3）将bicycle类的继承方式恢复为public，代码回到（1）的状态，再在bicycle类下面增加下第二层汽车类car的定义，car也是公有继承基类vehicle，其中增加了一个保护成员变量seatnum，表示汽车有几个座位，其定义方式与类bicycle类似。主函数中定义该类对象，观察运行结果。（4）在上一步基础上，再定义一个第三层类motorcycle，该类以公有方式继承了第二层的bicycle和car类。定义其构造函数，要调用两个直接基类的构造函数，再改选函数show(),输出所有四个成员变量的信息。主函数中只定义类motorcycle的对象并调用相应的函数，程序进行编译，会产生错误和警告，因为存在二义性问题，请采用把vehicle设置为虚基类人方法消除二义性，修改程序，观察运行结果。

在继承过程中，注意，如果不把vehicle设置为虚基类，会有什么问题？编程试试看。三、实验代码与调试结果（结果请截图）1#include<iostream>usingnamespacestd;classvehicle{protected:doublemaxspeed;doubleweight;public:vehicle(doublea,doubleb){ maxspeed=a; weight=b; cout<<"vehicle'sconstructorcalled"<<endl;} voidrun(){ cout<<maxspeed<<endl; } voidstop(){ maxspeed=0; cout<<maxspeed<<endl;} voidshow(){ cout<<maxspeed<<""<<weight<<endl; } doublegetmaxspeed(){returnmaxspeed;} doublegetweight(){returnweight;} ~vehicle(){ cout<<"vehicle'sdestructorcalled"<<endl;}};classbicycle:publicvehicle{protected:doubleheight;public:bicycle(doublea,doubleb,doublec):vehicle(a,b){height=c; cout<<"bicycle'sconstructorcalled"<<endl;} ~bicycle(){cout<<"bicycle'sdestructorcalled"<<endl;} voidshow(){ cout<<getmaxspeed()<<endl; cout<<getweight()<<endl; cout<<height<<endl;}};intmain(){ bicycleb(25,20,30); b.show();return0;}2errorC2274:'function-stylecast':illegalasrightsideof'.'operator原因：保护继承和私有继承都不能在类外调用基类的公有成员或保护成员3#include<iostream>usingnamespacestd;classvehicle{protected:doublemaxspeed;doubleweight;public:vehicle(doublea,doubleb){ maxspeed=a; weight=b; cout<<"vehicle'sconstructorcalled"<<endl;} voidrun(){ cout<<maxspeed<<endl; } voidstop(){ maxspeed=0; cout<<maxspeed<<endl;} voidshow(){ cout<<maxspeed<<""<<weight<<endl; } doublegetmaxspeed(){returnmaxspeed;} doublegetweight(){returnweight;} ~vehicle(){ cout<<"vehicle'sdestructorcalled"<<endl;}};classbicycle:publicvehicle{protected:doubleheight;public:bicycle(doublea,doubleb,doublec):vehicle(a,b){height=c; cout<<"bicycle'sconstructorcalled"<<endl;} ~bicycle(){cout<<"bicycle'sdestructorcalled"<<endl;} voidshow(){ cout<<getmaxspeed()<<endl; cout<<getweight()<<endl; cout<<height<<endl;}};classcar:publicvehicle{protected:intseatnum;public:car(doublea,doubleb,intc):vehicle(a,b){ seatnum=c; cout<<"car'sconstructorcalled"<<endl;} ~car(){cout<<"car'sdestructorcalled"<<endl;} voidshow(){ cout<<getmaxspeed()<<endl;cout<<getweight()<<endl; cout<<seatnum<<endl;}};intmain(){ bicycleb(25,20,30); b.show(); carc(10,20,30); c.show();return0;}4#include<iostream>usingnamespacestd;classvehicle{protected:doublemaxspeed;doubleweight;public:vehicle(doublea,doubleb){ maxspeed=a; weight=b; cout<<"vehicle'sconstructorcalled"<<endl;} voidrun(){ cout<<maxspeed<<endl; } voidstop(){ maxspeed=0; cout<<maxspeed<<endl;} voidshow(){ cout<<maxspeed<<""<<weight<<endl; } doublegetmaxspeed(){returnmaxspeed;} doublegetweight(){returnweight;} ~vehicle(){ cout<<"vehicle'sdestructorcalled"<<endl;}};classbicycle:virtualpublicvehicle{protected:doubleheight;public:bicycle(doublea,doubleb,doublec):vehicle(a,b){height=c; cout<<"bicycle'sconstructorcalled"<<endl;} ~bicycle(){cout<<"bicycle'sdestructorcalled"<<endl;} voidshow(){ cout<<getmaxspeed()<<endl; cout<<getweight()<<endl; cout<<height<<endl;} doublegetheight(){returnheight;}};classcar:virtualpublicvehicle{protected:intseatnum;public:car(doublea,doubleb,intc):vehicle(a,b){ seatnum=c; cout<<"car'sconstructorcalled"<<endl;} ~car(){cout<<"car'sdestructorcalled"<<endl;} voidshow(){ cout<<getmaxspeed()<<endl;cout<<getweight()<<endl; cout<<seatnum<<endl;} intgetseatnum(){returnseatnum;}};classmotorcycle:publicbicycle,publiccar{public: motorcycle(doublea,doubleb,doublec,intd):vehicle(a,b),bicycle(a,b,c),car(a,b,d){cout<<"motorcycle'sconstructorcalled"<<endl;} voidshow(){