指向类中多维数组的指针

Question

I'm trying to get to the bottom of an error, I wonder if you could help please? I'm having a bit of an issue with array pointers at the moment. I have three classes, one parent, and two children so to speak. One of the children has a 2D array of type struct, and I'm trying to access the elements of this from the other child.

I was wondering, is this code valid with the correct format/syntax for my array pointers? OChild1 creates and fills out the 2D array, I'm saving a pointer to that in Parent, and passing that pointer to OChild2, and then plan on using the contents of the array for further processing.

struct BOARDTILE
{
    float fPosX;
    float fPosY;

    BOARDTILES()
    {
        fPosX = 0.0f;
        fPosY = 0.0f;
    }
};

class CChild1
{
    public:
        BOARDTILE BoardTileArray[18][18];

    CChild1()
    {
    }

    writeBoardTileArray()
    {
        for (int i = 0; i <= 17; i++)
        {
            for (int j = 0; j <= 17; j++)
            {
                BoardTileArray[i][j].fPosX = (float) i * 5.0f;
                BoardTileArray[i][j].fPosY = (float) j * 7.0f;
            }
        }
    }
};

class CChild2
{
    public:
        BOARDTILE (*pBoardTileArray)[18][18];
        float fPosX;
        float fPosY;

    CChild2()
    {
    }

    void readBoardTileArray()
    {
        for (int i = 0; i <= 17; i++)
        {
            for (int j = 0; j <= 17; j++)
            {
                fPosX = (*pBoardTileArray[i][j]).fPosX;
                fPosY = (*pBoardTileArray[i][j]).fPosY;
                cout << fPosX;
                cout << fPosY;
            }
        }
    }

};

class CParent
{
    public:
        BOARDTILE (*pBoardTileArray)[18][18];
        CChild1 OChild1;
        CChild2 OChild2;

    CParent()
    {
        OChild1.writeBoardTileArray();
        pBoardTileArray = &(OChild1.BoardTileArray);
        OChild2.pBoardTileArray = pBoardTileArray;
    }
};

Answer 1

To store address of a two dimensional array, you would need a pointer to pointer,

Without typedef:
You would declare a member pointer as:

BOARDTILE (*pBoardTileArray)[18];

and then in the constructor, you would write:

    pBoardTileArray = OChild1.BoardTileArray;

But as you can see it makes the code complex. Using typedef can simplify it:

With typedef: (Recommended way)
With typedef you can write the following in the global scope:

typedef BOARDTILE BOARDTILE_ar18_t[18];

and then you can declare member pointer as:

BOARDTILE_ar18_t* pBoardTileArray;