C ++错误C2248：无法访问在SUPER类中声明的私有成员

Question

I have looked through similar questions from stackoverflow but haven't found an answer yet.

Here's my subclass declaration:

class Enemy : public Entity
{
public:
    Enemy();
    ~Enemy();
}; // This is the line that shows the error...

Here's my superclass declaration:

class Entity
{
//Member Methods:
public:
  Entity();
  ~Entity();

bool Initialise(Sprite* sprite);
void Process(float deltaTime);
void Draw(BackBuffer& backBuffer);

void SetDead(bool dead);
bool IsDead() const;

bool IsCollidingWith(Entity& e);

float GetPositionX();
float GetPositionY();

float GetHorizontalVelocity();
void SetHorizontalVelocity(float x); 

float GetVerticalVelocity();
void SetVerticalVelocity(float y);

protected:

private:
Entity(const Entity& entity);
Entity& operator=(const Entity& entity);

//Member Data:
public:

protected:
Sprite* m_pSprite;

float m_x;
float m_y;

float m_velocityX;
float m_velocityY;

bool m_dead;

private:

};

I already have a subclass called playership using the same structure, but that one works fine. So where could went wrong?

Answer 1

private:
Entity(const Entity& entity);
Entity& operator=(const Entity& entity);

You made the Entity class uncopyable and unassignalbe. But your enemy class doesn't have these member functions declared. So the compiler obliges and generates them for you. No problem so far, but I assume you then attempt to copy an enemy...

A minimal example for getting a similar error:

class Entity
{
//Member Methods:
public:
  Entity();
  ~Entity();

private:
Entity(const Entity& entity);
Entity& operator=(const Entity& entity);

};

class Enemy : public Entity
{
public:
    Enemy(){}
    ~Enemy(){}
};

int main()
{
  Enemy e1, e2 = e1;
  return 0;
}

Answer 2

Generally you cannot access private functions or constructor of superclass entity ,when you use object of a class first constructor of superclass is called and then constructor of subclass is called.

Here constructor of your superclass is declared as private.So, when you use sub class enemy first constructor of superclass entity is called and then constructor of sub class enemy is called .

In your code constructor of superclass entity is private which is called first when you use object of subclass enemy which cannot be accessed thats why error occur.