多继承类的虚函数表会有几张？

void testVTablePointers() {
    cout << "======= 测试不同类的对象大小 =======\n";
    cout << "sizeof(Vehicle): " << sizeof(Vehicle) << " bytes" << endl;
    cout << "sizeof(Electronic): " << sizeof(Electronic) << " bytes" << endl;
    cout << "sizeof(Navigable): " << sizeof(Navigable) << " bytes" << endl;
    cout << "sizeof(ElectricCar): " << sizeof(ElectricCar) << " bytes" << endl;
    cout << "sizeof(SmartElectricCar): " << sizeof(SmartElectricCar) << " bytes" << endl;
}

// 测试多继承下的指针转换
void testPointerCasting() {
    cout << "\n======= 测试多继承下的指针转换 =======\n";
    
    ElectricCar electricCar;
    
    cout << "\n1. ElectricCar对象地址: " << &electricCar << endl;
    
    // 转换为不同基类指针
    Vehicle* vehiclePtr = &electricCar;
    Electronic* electronicPtr = &electricCar;
    
    cout << "2. Vehicle* 指针值: " << vehiclePtr << endl;
    cout << "3. Electronic* 指针值: " << electronicPtr << endl;
    
    // 计算偏移量
    cout << "4. 两个指针的差值: " 
         << reinterpret_cast<char*>(electronicPtr) - reinterpret_cast<char*>(vehiclePtr) 
         << " 字节" << endl;
}

// 测试虚函数表的内容
void testVTableContent() {
    cout << "\n======= 测试虚函数表内容 =======\n";
    
    ElectricCar electricCar;
    
    // 获取Vehicle虚函数表
    typedef void(*FuncPtr)();
    void** vtable_vehicle = *(void***)&electricCar;
    
    cout << "Vehicle虚函数表内容：" << endl;
    cout << "  [0] vehicle_start: " << vtable_vehicle[0] << endl;
    cout << "  [1] vehicle_stop: " << vtable_vehicle[1] << endl;
    cout << "  [2] ~Vehicle: " << vtable_vehicle[2] << endl;
    
    // 获取Electronic虚函数表（需要偏移8字节）
    void** vtable_electronic = *(void***)((char*)&electricCar + 8);
    
    cout << "\nElectronic虚函数表内容：" << endl;
    cout << "  [0] electronic_powerOn: " << vtable_electronic[0] << endl;
    cout << "  [1] electronic_powerOff: " << vtable_electronic[1] << endl;
    cout << "  [2] ~Electronic: " << vtable_electronic[2] << endl;
    
    // 调用验证
    cout << "\n通过函数指针调用验证：" << endl;
    ((FuncPtr)vtable_vehicle[0])();  // 应该调用ElectricCar::vehicle_start
    ((FuncPtr)vtable_electronic[0])();  // 应该调用ElectricCar::electronic_powerOn
}

// 添加一些数据成员来观察构造顺序
class Vehicle {
public:
    int vehicle_id;
    Vehicle() : vehicle_id(1) {
        cout << "Vehicle constructor" << endl;
    }
    
};

class Electronic {
public:
    int electronic_id;
    Electronic() : electronic_id(2) {
        cout << "Electronic constructor" << endl;
    }
    
};

void testConstructionOrder() {
    cout << "\n======= 测试构造和析构顺序 =======\n";
    cout << "创建ElectricCar对象：" << endl;
    ElectricCar ec;
    cout << "\n销毁ElectricCar对象：" << endl;
}

class Vehicle {
public:
    void start() {
        cout << "Vehicle::start()" << endl;
    }
};

class Electronic {
public:
    void start() {  // 同名函数！
        cout << "Electronic::start()" << endl;
    }
};

class ElectricCar : public Vehicle, public Electronic {
public:
    void test() {
        // start();  // 错误！二义性，不知道调用哪个
        Vehicle::start();  // 正确：明确指定基类
        Electronic::start();  // 正确：明确指定基类
    }
};

class ElectricCar : public Vehicle, public Electronic {
public:
    using Vehicle::start;  // 引入Vehicle::start到当前作用域
    // 现在可以直接调用start()，会调用Vehicle::start()
};

// 接口类
class IReadable {
public:
    virtual void read() = 0;
};

class IWritable {
public:
    virtual void write() = 0;
};

// 文件类实现两个接口
class File : public IReadable, public IWritable {
public:
    void read() override { /* ... */ }
    void write() override { /* ... */ }
};

// 混入类：提供序列化功能
class Serializable {
public:
    virtual string serialize() = 0;
};

// 混入类：提供日志功能
class Loggable {
public:
    virtual void log() = 0;
};

// 业务类通过多继承获得这些功能
class User : public Serializable, public Loggable {
    // ...
};