Indomitable beast: a 2d char array, inside a structure, in the belly of an unmanaged dll

问题

Having gird my loins and ventured into Legacy Land, having hacked, p-invoked and marshaled every type of wild beast, I now stand before a creature so fierce that, as far as I can tell from an exhausting survey of my brethern-in-arms, not a single code warrior has been left standing.

Here are the details. I am attempting to pass a 2d char array (in c#), inside a structure, to a C dll (no source code), which must be able to make changes to the 2d array.

The C structure:

typedef struct s_beast
{
    bool fireBreathing;
    char entrails[30][50];
} Beast;

Here is what I have so far in C#, but it is (incorrectly) a 1d array:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Beast
{
    public BOOL fireBreathing;

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 30 )]
    public char [] entrails;
}

Who is willing to take a stab at this and, for my sake, the sake of my brethern, and for the sake of future generations, once and for all slay this beast?

回答1:

Interop isn't my strong suite, but C-style multi-dimension arrays are essentially just a syntactic difference on single-dimension arrays.

Something like this may work:

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Beast
{
    public BOOL fireBreathing;

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 1500 )] /* 50x30 */
    public char [] entrails;
}

public class TamedBeast
{
    public Beast WildBeast;
    public char[30][50] entrails
    {
      var 2dEntrails = new char[30][50];
      var position = 0;
      for (int first = 0; first <30; first++)
      {
         for (int second = 0; second <50; second++)
         {
             2dEntrails[first][second] = WildBeast.entrails[position++];
         }
      }
      return 2dEntrails;
    }
}

Disclaimer: Untested code from memory, but it should give some ideas. This could cache the 2D array, I didn't just as an initial stab at the beast, plus syncing updates. This can probably be sped up considerably with mem copy operations for each 2nd dimension.

来源：https://stackoverflow.com/questions/11571907/indomitable-beast-a-2d-char-array-inside-a-structure-in-the-belly-of-an-unman