How to export c++ data Structure to vb.net?

EDN Admin · May 30, 2012

Hi,
I have some work related with data decompression and memory mapping.The decompression and memory mapping in c++ code is working fine . Now i want to convert the code in vb.net.
In vb.net i am able to decompress the data the moment i try to unmarshal the data to structure is gives error -
"Could not load type MARKETPIC from assembly McxRecv, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null because it contains an object field at offset 118 that is incorrectly aligned or overlapped by a non-object field."
Vb.net Structures
_________________
<StructLayout(Runtime.InteropServices.LayoutKind.Explicit, Size:=21, CharSet:=CharSet.Ansi, pack:=1)> _ 
Structure BROADCASTMessageHeader Message Header Total Length is 21 
 
<FieldOffset(0)> Dim ExchangeTime As Int32 
<FieldOffset(4)> Dim MessageCode As Int16 
<FieldOffset(6)> Dim Reserved1 As Int16 
<FieldOffset(8)> Dim reservedT1 As Double 
<FieldOffset(16)> Dim reservedT2 As Byte 
<FieldOffset(17)> Dim MessageSize As Int16 
<FieldOffset(19)> Dim Reserved3 As Int16 
 
End Structure

<StructLayout(Runtime.InteropServices.LayoutKind.Explicit, Size:=14, CharSet:=CharSet.Ansi, pack:=1)> _ 
Structure ORDERBYPRICE 
<FieldOffset(0)> Dim qty As Int32 
<FieldOffset(4)> Dim OrderPrice As Int32 
<FieldOffset(8)> Dim TotalNoOFOrder As Int32 
<FieldOffset(12)> Dim Reserved As Int16 
End Structure

 
<StructLayout(Runtime.InteropServices.LayoutKind.Explicit, Size:=248, CharSet:=CharSet.Ansi)> _ 
Private Structure MARKETPIC 
<FieldOffset(0)> Dim BroadcastmsgHeader As BROADCASTMessageHeader 21 
<FieldOffset(21)> Dim IndicativePriceVolume As Byte 
<FieldOffset(22)> Dim InstrumentIdentifier As Int32 
<FieldOffset(26)> Dim Reserved2 As Byte 
<FieldOffset(27)> Dim IndexFlag As Byte 
<FieldOffset(28)> Dim TotalQtyTraded As Int32 
<FieldOffset(32)> Dim LastTradedPrice As Int32 
<FieldOffset(36)> Dim LastTradedQty As Int32 
<FieldOffset(40)> Dim LastTradTime As Int32 
<FieldOffset(44)> Dim AvgTradePrice As Int32 
<FieldOffset(48)> <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPArray, SizeConst:=70)> Dim BuyOrderPrice() As ORDERBYPRICE 
<FieldOffset(118)> <System.Runtime.InteropServices.MarshalAsAttribute(System.Runtime.InteropServices.UnmanagedType.LPArray, SizeConst:=70)> Dim SellOrderPrice() As ORDERBYPRICE 
 
<FieldOffset(188)> Dim TotalBuyQty As Double 
<FieldOffset(196)> Dim TotalSellQty As Double 
<FieldOffset(204)> Dim reserved As Int16 
<FieldOffset(199)> <VBFixedString(2)> Dim reserved As String 
<FieldOffset(206)> Dim ClosePrice As Int32 
<FieldOffset(210)> Dim OPrice As Int32 
<FieldOffset(214)> Dim High As Int32 
<FieldOffset(218)> Dim Low As Int32 
<FieldOffset(222)> Dim Reserved32 As Int16 
<FieldOffset(224)> Dim OPENINTEREST As Int32 
<FieldOffset(228)> Dim TotalTrades As Int32 
<FieldOffset(232)> Dim HighestPriceEver As Int32 
<FieldOffset(236)> Dim LowestPriceEver As Int32 
<FieldOffset(240)> Dim TotalTradedValue As Double 
 
End Structure

The Code for memory mapping in vb.net

Public Shared Function RawDeserialize(ByVal rawdatas As Byte(), ByVal anytype As Type) As Object 
Dim rawsize As Integer = Marshal.SizeOf(anytype) 
If rawsize > rawdatas.Length Then 
Return Nothing 
End If 
Dim buffer As IntPtr = Marshal.AllocHGlobal(rawsize) 
Marshal.Copy(rawdatas, 0, buffer, rawsize) 
Dim retobj As Object = Marshal.PtrToStructure(buffer, anytype) 
Marshal.FreeHGlobal(buffer) 
Return retobj 
End Function 

c++ Structure
________________
struct BroadcastMessageHeader // Total Size is 21 
{ 
<span style="white-space

re long ExchangeTime; 
<span style="white-space

re short MessageCode; 
<span style="white-space

re short Reserved1; 
<span style="white-space

re char Reserved2[9]; 
<span style="white-space

re short MessageSize; 
<span style="white-space

re short Resderved3; 
}; 
struct OrderByPrice //total size is 14 Byte 
{ 
<span style="white-space

re long Quantity; 
<span style="white-space

re long OrderPrice; 
<span style="white-space

re long TotalNumberOfOrders; 
<span style="white-space

re short Reserved; 
};
struct MarketPicture // MessageCode = 31038 
{ 
<span style="white-space

re //MessageHeader Header; 
<span style="white-space

re BroadcastMessageHeader BroadcastMsg; 
<span style="white-space

re unsigned char IndicativePriceVolume; 
<span style="white-space

re long InstrumentIdentifier; 
<span style="white-space

re char Reserved1; 
<span style="white-space

re char IndexFlag; 
<span style="white-space

re long TotalQtyTraded; 
<span style="white-space

re long LastTradedPrice; 
<span style="white-space

re long LastTradedQty; 
<span style="white-space

re long LastTradedTime; 
<span style="white-space

re long AverageTradePrice; 
<span style="white-space

re OrderByPrice BestBuy[5]; 
<span style="white-space

re OrderByPrice BestSell[5]; 
<span style="white-space

re double TotalBuyQty; 
<span style="white-space

re double TotalSellQty; 
<span style="white-space

re char Reserved2[2]; 
<span style="white-space

re long ClosePrice; 
<span style="white-space

re long OpenPrice; 
<span style="white-space

re long HighPrice; 
<span style="white-space

re long LowPrice; 
<span style="white-space

re short Reserved3; 
<span style="white-space

re long OI; 
<span style="white-space

re long TotalTrades; 
<span style="white-space

re long HighestPriceEver; 
<span style="white-space

re long LowestPriceever; 
<span style="white-space

re double TotalTradedVol; 
};

The c++ code is working perfectly

Please help.....
<hr class="sig Shail

View the full article

How to export c++ data Structure to vb.net?

EDN Admin

Well-known member

Similar threads