C# 调用DLL 参数包括结构,结构中包括结构数组,且有定长字符串

Question

各位高手好,问题如下:
struct HY_RECT_S
{
long lLeft;
long lRight;
long lTop;
long lBottom;
}; struct ID_CARD_S
{
  char szText[10][256];
  HY_RECT_S idRect[10];
};long __stdcall Get_IdcData(int iCardType, char* szFileNameIn, char *szFullFileNameOut, char *szHeadFileNameOut, ID_CARD_S* pstOut);我在C#中的定义如下:
[StructLayout(LayoutKind.Sequential)]
        public struct HY_RECT_S
        {
            public Int32 lLeft;
            public Int32 lRight;
            public Int32 lTop;
            public Int32 lBottom;            public void Initialize()
            {
                lLeft = 0;
                lRight = 0;
                lTop = 0;
                lBottom = 0;
            }
        }        [StructLayout(LayoutKind.Sequential)]
        public struct ID_CARD_S
        {
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
            public string[] szText;            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)]
            public HY_RECT_S[] idRect;            public void Initialize()
            {
                //初始化数组大小
                szText = new string[10];
                idRect = new HY_RECT_S[10];                //初始化数组中每个元素的长度或值
                for (int i = 0; i < szText.Length; i++)
                {
                    //szText[i] = (new char[256]).ToString();                    StringBuilder buffer = new StringBuilder(256);                    for (int j = 0; j < 256; j++)
                    {
                        buffer.Append((char)0);
                    }
                    //buffer.Append('*', buffer.Capacity - 1);
                    //buffer.Append((char)0, buffer.Capacity - 1);
                    szText[i] = buffer.ToString();                    //buffer.Append('*', buffer.Capacity - 8);
                }                for (int i = 0; i < idRect.Length; i++)
                {
                    idRect[i].Initialize();
                }
          }//初始化结束
       }对DLL的声明如下:
[DllImport("Dll\\IDRCore.dll", EntryPoint = "Get_IdcData", CharSet = CharSet.Ansi)]
            public static extern Int32 Get_IdcData(Int32 iCardType, [In] string szFileNameIn, [Out] string szFileNameOut, [Out] string szHeadFileNameOut, [In, Out] ref ID_CARD_S pstOut);调用:
IDRCore.ID_CARD_S sCard=new IDRCore.ID_CARD_S();
            sCard.Initialize();            int iret;
            iret=IDRCore.Get_IdcData(1, Application.StartupPath + "\\1.bmp",Application.StartupPath+ "\\2.bmp",Application.StartupPath+ "\\3.bmp", ref sCard);问题:
调用过程没有报错,但在关闭时系统报错,而且szText没有值,可能是内存问题,请问以上对结构的声明有问题吗?
看过微软PINVOKELIB.DLL的调用例子,但好象没有这么复杂的例子.
这个应用的难点是:1、使用了结构，2、结构中包括结构数组，3、结构中包括定长字符串数组，
请高人指点一下，不胜感激。

Answer 1

        public struct ID_CARD_S 
        { 
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 10)] 
            public string[] szText;                                    //<----
        ...
Thie one has problem.
char szText[10][256]; means an array of continuous 2560 bytes,
however, in your C# definition, string[] szText are ten 'pointers' that point to
ten seperated strings.To overcome this problem,
Method 1: you can simply use byte array[MarshalAs(UnmanagedType.ByValArray, SizeConst = 2560]
public byte[] szText;
After the result is returned, you then parse the byte array into strings.Method 2: you can provide a custom Marshaler.
You can google ICustomMarshaler. Or, I can provide you an example in case you are really interested in it.
 

Answer 2

har szText[10][256]; means an array of continuous 2560 bytes, 不一定