请使用VC6或使用[答题]菜单打开考生文件夹proj2下的工程proj2,其中定义了vehicle类,并派生出motorcar类和bicycle类。然后以motorcar和bicycle作为基类,再派生出motorcycle类。要求将vehicle作为虚基类,避免二义性问题。请在程序中的横线处填写适当的代码并删除横线,以实现上述类定义。此程序的正确输出结果应为:
80
150
100
1
注意:只能在横线处填写适当的代码,不要改动程序中的其他内容,也不要删除或移动“// ****found****”。
#include <iostream.h>
class vehicle
private:
int MaxSpeed;
int Weight;
public:
//**********found**********
vehicle (int maxspeed,intweight):______
~vehicle();
int getMaxSpeed()return MaxSpeed;
int getWeight()return Weight;
;
//**********found**********
class bicycle:______public vehicle
private:
int Height;
public:
bicycle(int maxspeed,int weight,int height):vehicle(maxspeed,weight),Height(height)
int getHeight()return Height;;
;
//**********found**********
class motorcar:______public vehicle
private:
int SeatNum;
public:
motorcar(int maxspeed,int weight,int seatnum):vehicle(maxspeed,weight),SeatNum(seatnum)
int getSeatNum()return SeatNum;;
;
//**********found**********
class motorcycle:______
public:
motorcycle(int maxspeed,intweight,int height):vehicle (maxspeed,weight),bicycle(maxspeed,weight,height),motorcar(maxspeed,weight,1)
;
void main ()
motorcycle a(80,150,100);
cout<<a.getMaxSpeed()<<endl;
cout<<a.getWeight()<<endl;
cout<<a.getHeight()<<endl;
cout<<a.getSeatNum()<<endl;
参考答案:
(A)MaxSpeed(maxspeed),Weight(weight){};
(B)virtual
(C)virtual
(D)public bicycle,public motorcar
解析:
本题考查vehicle类及其派生类motorcar和bicycle,再由这两类派生出motorcycle类,其中涉及构造函数、成员函数和析构函数。构造函数采用成员初始化列表来完成对私有成员的初始化,派生类的书写要注意关键字。
(1)主要考查考生对构造函数的掌握,构造函数使用初始化列表来对私有成员MaxSpeed和Weight初始化。
(2)主要考查考生对派生类的掌握,题目要求将vehicle作为虚基类,避免二义性问题。因此在这里添加virtual使vehicle成为虚基类。
(3)主要考查考生对派生类的掌握,题目要求以motorcar和bicycle作为基类,再派生出motorcycle类。在主函数中可以看到motorcycle类的实例a调用getHeight函数和getSeat-Num函数,由此可知这两个基类都是公有继承,因此得出语句:public bicycle,public motorcar。
虚基类继承时要添加关键字virtual,以避免二义性。