2 dimensional array of managed object c++

Question

I am attempting to create a grid of hexagons on a windows form.

To do this i have created a 'hexagon' class with the header file as follows:

ref class Hexagon
{
public:
    Hexagon(int X, int Y, int I, int J);
    Hexagon();
private:
    array<Point>^ vertices;
    Point Centre;
    int i, j;
public:
    int GetX();
    int GetY();
    void SetCentre(int X, int Y);
    void CalculateVertices();
    array<Point>^ GetVertices();
    void drawHexagon();
};

i then want to have a 2 dimensional array storing these hexagons. my attempt at doing this is as follows:

array<Hexagon^,2>^ Grid

but i get the 'a variable with static storage duration cannot have a handle or tracking reference type'

how do i create a 2d array to add hexagons to?

is it not?! im doing it in a c++ file using a c++ compiler in visual studio 2012, im just using .NET DLL? — JabbaWook
– JabbaWook, Commented Mar 2, 2014 at 15:55
Definitely not. It is probably some kind of hybrid language supporting some part of C++ syntax. But this code is not valid C++. — juanchopanza
– juanchopanza, Commented Mar 2, 2014 at 16:02
just done a quick bit of research - the language is not called C++, it's called C++/CLI. One reason why it's called thus might be that plain C++ is a complete subset of C++/CLI (i.e. any conformant C++ program is also a conformant C++/CLI program). — JabbaWook
– JabbaWook, Commented Mar 2, 2014 at 16:18
@JabbaWook I would advise you to rely on "regular" c++ if you dont have any good reason to use this extension. — Sebastian Hoffmann
– Sebastian Hoffmann, Commented Mar 2, 2014 at 16:23

Hans Passant · Accepted Answer · 2014-03-02 16:34:03Z

4

A ref class declares a class which is managed by the garbage collector. One strong restriction that the C++/CLI compiler applies to such declarations is that such class cannot contain non-managed objects. That very often turns out poorly when the object is moved when the heap is compacted, invalidating unmanaged pointers to such non-managed objects.

The likely trouble-maker is the Point type, there are no other candidates. A sample declaration for a managed Point type that doesn't have this problem is:

   public value struct Point {
       int x, y;
   };

Or use the baked-in System::Drawing::Point type instead.

answered Mar 2, 2014 at 16:34

Hans Passant

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