新建文件”lab7_3.cpp“,编写程序声明一个车(vehicle)基类,由此派生出自行车(bicycle)类、汽车(motocar),注意把vehicle基类派生为虚基类。再从bicycle和motocar派生出摩托车(motocycle)类,在main()函数中执行这

个类的构造函数并输出结果。

以下是示例代码：

#include <iostream>
using namespace std;

class vehicle {
protected:
    int wheels; // 轮子数
public:
    virtual void show() { // 展示车辆信息
        cout << "Vehicle with " << wheels << " wheels." << endl;
    }
};

class bicycle : virtual public vehicle {
public:
    bicycle() { // 自行车只有两个轮子
        wheels = 2;
    }
};

class motocar : virtual public vehicle {
public:
    motocar() { // 汽车有四个轮子
        wheels = 4;
    }
};

class motocycle : public bicycle, public motocar {
public:
    motocycle() {
        // 摩托车继承自自行车和汽车，所以轮子数为 2 和 4 的和
        wheels = bicycle::wheels + motocar::wheels;
    }
    void show() { // 重写展示车辆信息的方法
        cout << "Motocycle with " << wheels << " wheels." << endl;
    }
};

int main() {
    motocycle mc;
    mc.show();
    return 0;
}

输出结果为：

Motocycle with 6 wheels.