Обработка вложенных структур из неуправляемого cpp в управляемый c # с использованием IntPtr

Я пытаюсь присвоить значения массиву структуры в управляемом c # и доступ к нему в cpp.

Рассмотрим следующие структуры в cpp:

struct NSCASR_RCG_ITEM_ST
{
char* pstrSlotName;
char* pstrReportedText;
short usConfidence;
unsigned long ulLocation;
unsigned long ulDuration;
};

struct NSCASR_RCG_PHRASE_ST
{
unsigned short usConfidence;
unsigned short usNumItems;
short sGrammarIndex;
short sGrammarType;
NSCASR_RCG_ITEM_ST Item[1];
};

struct NSCASR_RCG_RES_ST
{
unsigned long ulSizeBytes;
unsigned long ulWarnings;
unsigned short usNumPhrases;
char*  pstrWaveformURI;
unsigned long ulWaveformSizeBytes;
unsigned long ulWaveformDuration;
NSCASR_RCG_PHRASE_ST * pPhrase[1];
};

Рассмотрим следующие структуры в c #:

[StructLayout(LayoutKind.Explicit,CharSet = CharSet.Ansi)]
public struct NSCASR_RCG_ITEM_ST
{
[FieldOffset(0)]
public IntPtr pstrSlotName;
[FieldOffset(4)]
public IntPtr pstrReportedText;
[FieldOffset(8)]
public ushort usConfidence;
[FieldOffset(10)]
public uint ulLocation;
[FieldOffset(14)]
public uint ulDuration;
}

[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Ansi)]
public struct NSCASR_RCG_PHRASE_ST
{
[FieldOffset(0)]
public ushort usConfidence;
[FieldOffset(2)]
public ushort usNumItems;
[FieldOffset(4)]
public short sGrammarIndex;
[FieldOffset(6)]
public short sGrammarType;
[FieldOffset(8)]
public IntPtr Item;/*This holds pointer to NSCASR_RCG_ITEM_ST*/
}[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Ansi)]
public unsafe struct NSCASR_RCG_RES_ST
{

[FieldOffset(0)]
public uint ulSizeBytes;
[FieldOffset(4)]
public uint ulWarnings;
[FieldOffset(8)]
public ushort usNumPhrases;
[FieldOffset(12)]
public IntPtr pstrWaveformURI;
[FieldOffset(16)]
public uint ulWaveformSizeBytes;
[FieldOffset(20)]
public uint ulWaveformDuration;
[FieldOffset(24)]
public IntPtr pPhrase;/*This holds pointer to NSCASR_RCG_PHRASE_ST*/
}

Используя вышеупомянутые структуры, я присваиваю значения членам структуры NSCASR_RCG_ITEM_ST следующим образом:

public unsafe static int ASR_Recognize_ResultsGet(ref Constants.NSCASR_RCG_RES_ST pRecognitionResults)
{
Constants.NSCASR_RCG_PHRASE_ST[] test = new Constants.NSCASR_RCG_PHRASE_ST[1];
Constants.NSCASR_RCG_ITEM_ST[] itm = new Constants.NSCASR_RCG_ITEM_ST[1];
itm[0].pstrSlotName = Marshal.StringToHGlobalAnsi("123");
itm[0].pstrReportedText = Marshal.StringToHGlobalAnsi("456");
itm[0].usConfidence = 789;
itm[0].ulLocation = 888;
itm[0].ulDuration = 999;

GCHandle arrHandle = GCHandle.Alloc(test, GCHandleType.Pinned);
GCHandle itmhandle = GCHandle.Alloc(itm, GCHandleType.Pinned);

try
{
test[0].Item = itmhandle.AddrOfPinnedObject();
pRecognitionResults.pPhrase = arrHandle.AddrOfPinnedObject();
}
catch (Exception ex)
{

}
finally
{
arrHandle.Free();
itmhandle.Free();
}
}

Но я не могу получить доступ к данным в cpp.
Ниже приведен код cpp, где я получаю доступ к членам

NSCASR_RCG_RES_ST phrase[2] = { 0 };
int _tmain()
{
int *result;

NSCASR_RCG_PHRASE_ST * ptr1;
NSCASR_RCG_RES_ST *rec = (NSCASR_RCG_RES_ST *)phrase;
NSCASR_RCG_ITEM_ST item[1];

ASR_Recognize_ResultsGet(rec);

ptr1 = rec->pPhrase[0];
for (int i = 0; i < 10; i++)
{
printf("\n%d--%s", i, ptr1[i].Item[i].pstrSlotName);
printf("\n%d--%s", i, ptr1[i].Item[i].pstrReportedText);
printf("\n%d--%d", i, ptr1[i].Item[i].usConfidence);
printf("\n%d--%d", i, ptr1[i].Item[i].ulLocation);
printf("\n%d--%d", i, ptr1[i].Item[i].ulDuration);
printf("\n%d--%d", i, ptr1[i].Item[i].usConfidence);
}
return 0;
}