如何从类中实例化的对象访问私有变量

问题描述：

我试图更改一个类中的一个私有变量，该类在对象内部初始化。
我的意图可以从下面的简单例子中得出。
从 obj 调用增量$ c>应该增加 BaseClass :: stuff 。

I am trying to change a private variable of a class inside an object, which is initialized inside that class. My intention can be drawn from the simple example below. the Increment called from obj should increase the BaseClass::stuff.

template <typename ObjectType>
class BaseClass{
 public:

  int Increment(){
    return obj.Increment();
  }

 private:
  int stuff = 0;
  ObjectType obj;
};

class ObjectType{
  public:     
   int Increment ()
   {
      return BaseClass<ObjectType>::stuff++;
   };
};

int main () {
  BaseClass<ObjectType> base;
  base.Increment(); // should increase stuff by 1;
}

我可以想到的一种方法是将参数传递给 obj.Increment（）。

One way I can think of is passing stuff as parameter to obj.Increment().

有没有一种方法，我可以实现这个而不传递作为参数？

Is there a way I can achieve this without passing it as a parameter?

答

您的示例有一些错误。

修复并添加了朋友说明符后，应该如下所示：

Your example had a few errors.
Once fixed and added a friend specifier, it should look like this:

template <typename ObjectType>
class BaseClass{
public:
    friend ObjectType;

    int Increment(){
        return obj.Increment();
    }

private:
    static int stuff;
    ObjectType obj;
};

template<typename T>
int BaseClass<T>::stuff = 0;

class ObjectType{
public:     
    int Increment ()
    {
        return BaseClass<ObjectType>::stuff++;
    };
};

int main () {
    BaseClass<ObjectType> base;
    base.Increment(); // should increase stuff by 1;
}

如何从类中实例化的对象访问私有变量

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