#include<iostream> using namespace std; class Vehicle { protected: int speed; int wheel; public: Vehicle(){} virtual void Display() = 0; }; class Bicycle :virtual public Vehicle { public: Bicycle(int s, int w) { s = speed, w = wheel; } void Display() { cout << "Bicycle:" << speed << "," << wheel << endl; } }; class Car :virtual public Vehicle { public: Car(int s, int w) { s = speed, w = wheel; } void Display() { cout << "Car:" << speed << "," << wheel << endl; } }; class Motocycle :public Bicycle, public Car { public: Motocycle(int s, int w):Bicycle(s,w),Car(s,w){} void Display() { cout << "Motocycle:" << speed << "," << wheel << endl; } }; int main() { Bicycle b(20, 2); b.Display(); Car c(40, 4); c.Display(); Motocycle m(30, 2); m.Display(); return 0; }运行结果为什么不对

程序的运行结果不对是因为在 Bicycle 和 Car 类的构造函数中，将传入的参数赋值给了成员变量时，出现了错误。正确的做法应该是将成员变量和传入的参数名字进行区分，如下所示：

class Bicycle :virtual public Vehicle {
public:
    Bicycle(int s, int w) { speed = s, wheel = w; }
    void Display() { cout << "Bicycle:" << speed << "," << wheel << endl; }
};

class Car :virtual public Vehicle {
public:
    Car(int s, int w) { speed = s, wheel = w; }
    void Display() { cout << "Car:" << speed << "," << wheel << endl; }
};

在 Motocycle 类的构造函数中也需要对 Bicycle 和 Car 的构造函数进行调用，正确的写法如下：

Motocycle(int s, int w):Bicycle(s,w),Car(s,w),Vehicle(){}

修改后的程序运行结果如下：

Bicycle:20,2
Car:40,4
Motocycle:30,2

相关问题

#include<iostream> using namespace std; class vehicle { private: int MaxSpeed; int Weight; public: virtual void Run() { cout<<"Run"<<endl; } virtual void Stop() { cout<<"Stop"<<endl; } }; class bicyle:public vehicle { private: int Height; }; class motorcar:public vehicle { private: int SeatNum; }; class motocycle { }; int main(){ motocycle a; a.Run(); a.Stop(); return 0; }有什么问题

在这段代码中，motocycle类没有继承vehicle类，因此它没有Run()和Stop()方法。在main()函数中，使用motocycle类的对象a调用Run()和Stop()方法是不合法的。如果想要使用Run()和Stop()方法，可以让motocycle类继承vehicle类或者让motocycle类成为vehicle类的派生类之一。

补充以下代码，完成函数定义，使其可以正常执行。 #include<iostream> using namespace std; class vehicle{ protected: int size; int speed; public: void set(int s){ speed=s; } （1） get(){ return speed/10; } }; class car:public vehicle{ public: int get(){ return speed; } }; class truck:public vehicle{ public: int get(){ return speed/2; } }; int max( （2） ){ //形参为引用类型 if(v1.get()>v2.get()) return 1; else return 2; } int main() { truck t; car c; t.set(160); c.set(80); cout<<max(t,c)<<endl; //输出：2 return 0; }

下面是补充完整的代码：

#include<iostream> 
using namespace std; 

class vehicle{ 
protected: 
    int size; 
    int speed; 
public: 
    void set(int s){ 
        speed=s; 
    } 
    int get(){ 
        return speed/10; 
    } 
}; 

class car:public vehicle{ 
public: 
    int get(){ 
        return speed; 
    } 
}; 

class truck:public vehicle{ 
public: 
    int get(){ 
        return speed/2; 
    } 
}; 

int max(vehicle& v1, vehicle& v2){  // 形参为引用类型
    if(v1.get()>v2.get()) 
        return 1; 
    else 
        return 2; 
} 

int main() 
{ 
    truck t; 
    car c; 
    t.set(160); 
    c.set(80); 
    cout<<max(t,c)<<endl;   // 输出：2 
    return 0; 
}

需要注意的是：

1. 在 `vehicle` 类中，`get()` 函数返回的是 `speed/10`，所以其返回值类型应该是 `int`。

2. 在 `max()` 函数中，参数类型应该是 `vehicle&`，即引用类型。

3. 在 `car` 和 `truck` 类中，都重载了 `get()` 函数，返回不同的值。