c++ - 为什么访问同一个类的私有(private)成员时会编译出错

Question

为什么这个程序会出现编译错误:

proxy.cpp: 在成员函数‘void ProxyCar::MoveCar()’中:proxy.cpp:59: 错误:'int Driver::age' 是私有(private)的proxy.cpp:81: 错误:在此上下文中

class Car
{
    public:
        void MoveCar()
        {
                cout << "Car has been driven";
        }
};

class Driver
{
    private:
         int age;

    public:

        int get() { return age; }
        void set(int value) { age = value; }
        Driver(int age):age(age){}
};

class ProxyCar
{
    private:
        Driver driver;
        Car *realCar;

    public:
    ProxyCar(Driver driver): driver(driver), realCar (new Car) {}

    void MoveCar()
    {
        if (driver.age <= 16)
          cout << "Sorry the driver is too young to drive";
        else
            realCar->MoveCar();
    }
};

int main()
{
        Driver d(16);
        ProxyCar p(d);
        p.MoveCar();
        return 0;
}

我正在尝试访问 ProxyCar 中的 Driver 对象。此行导致错误。 如果(司机年龄 <= 16)

Answer 1

因为 age 是 Driver 类中的私有(private)成员。

你打算这样做吗:

     if (driver.get()<= 16)
         cout << "Sorry the driver is too young to drive";
     else
         realCar->MoveCar();