向量<Class>没有成员“功能”

Question

I have two classes (Vector3 is an irrelevant class here):

class Room {
  public:
    Room();

  private:
    vector<Button> roombuttons[3];
};

and

class Button {
  public:
    Button();
    Button(Vector3 pos);

    void SetPos(Vector3 pos);

  private:
    Vector3 pos;
}

If I want to define Room() as:

Room::Room() { 
  roombuttons[0].SetPos(100,100,0);
}

I get an error saying class "std::vector<Button, std::allocator<Button>>" has no member "SetPos" Why am I not able to call the SetPos function of the Button class on Button instances in a vector?

I want to have a Room instance with a couple Buttons that are stored in some kind of array so that I can use them like elements of an array.

Answer 1

The problem is that you are declaring roombuttons as an array of vector objects, thus roombuttons[0] is accessing the 1st vector , not the 1st Button . So the error is correct, vector does not have a method named SetPos() . You would need something more like this instead:

roombuttons[0][0].SetPos(100,100,0);

But that is not what you are really asking for. You want an array of Button s, so either

• change your array to be a single vector instead, and then populate it in the constructor:

   class Room { public: Room(); private: vector<Button> roombuttons; }; Room::Room() : roombuttons(3) { roombuttons[0].SetPos(100,100,0); ... }

• or, just get rid of the vector since you know up front how many Button s you want:

   class Room { public: Room(); private: Button roombuttons[3]; }; Room::Room() { roombuttons[0].SetPos(100,100,0); ... }

Answer 2

just do

vector<Button> roombuttons;

instead of

vector<Button> roombuttons[3];