Question

i use a c function in a (.dll) file that takes a reference to array of struct and returns a byte that determines whether my operation is succeed or not.
it works well in the c project
and worked well when i send a small size array(up to 7 elements)
and false after that !!

the array is from the following struct

    [StructLayout(LayoutKind.Sequential)]
    public struct MainStruct
    {
        [MarshalAsAttribute(UnmanagedType.Struct, SizeConst = 5)]
        public Struct2 Struct2Object;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem1;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem2;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem3;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem4;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem5;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem6;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem7;

        [MarshalAsAttribute(UnmanagedType.U8, SizeConst = 1)]
        public UInt64 Elem8;

    };

Answer 1

    __declspec(dllexport) TU08 GetBuffer(MainStruct *OBJ)
    {
    TU64 SelectedOBIS;
    TU08 XdrBuffer[Dlms_mXdrMaxBuffer];
    TU08 *pXdrBuffer;
    TU32 i;
    TU32 NumberOfElements;

    pXdrBuffer = XdrBuffer;
    SelectedOBIS = ProfilesData[LOG_ID_1].ProfilesOBISCodes;

        pXdrBuffer = XdrBuffer;
        Dlms_gXdrInitBuffer();
        /////// Get Data ///////
        if(Main_iSendGetRequest(SelectedOBIS, 7, 2, XdrBuffer) == false)
            return 0;
        /////// Extract Data ///////
        if(*XdrBuffer == Dlms_mXdrArray)
        {
            NumberOfElements = *(pXdrBuffer + 1);
            pXdrBuffer += 2; // 2 for array tag and its number of fields 
            for(i=0; i<NumberOfElements; i++)
            {
                if(*pXdrBuffer == Dlms_mXdrStruct)
                {
    pXdrBuffer += 2; // 2 for struct tag and its number of fields 
    pXdrBuffer = gGetDateTime(pXdrBuffer, &OBJ[i].TimeStamp);
    pXdrBuffer = gGetLongUnsigned(pXdrBuffer, &OBJ[i].StatusRegister);
    pXdrBuffer = gGetUnsigned(pXdrBuffer, &OBJ[i].EventCode);
    }
            }
        }
    return 1;
}

that`s the used function.

and this is the struct in C

typedef struct
{
    Struct2 Struct2OBject;
    TU64 Elem1;
    TU64 Elem2;
    TU64 Elem3;
    TU64 Elem4;
    TU64 Elem5;
    TU64 Elem6;
    TU64 Elem7;
    TU64 Elem8;
} MainStruct;

the marshal of the function is

    [DllImport("dll.dll", CallingConvention = CallingConvention.Cdecl)]
    public static extern byte GetBuffer([In, Out] MainStruct[] Profile);

the point is that it works well in C and works well in the windows form application too if the size of the array passed to the function is 7 or less !