Can anyone help me insure this C# structure is identical to this C++ one?

rmathis

23y6.1k.NET

Hello. I need to make an identical c# struct compared to a C++ struct. Can someone just look at the two and tell me if they should be the same size, values, etc? Here is the C++ version { DWORD packid; long price; long valPrice; BYTE byInvIndex; BYTE nothing; // filler to cause word alignment. WORD numCards; WORD packType; } PACKED PACKENTRY; // Database struct typedef PREFIX_PACKED struct { DWORD crc32; WORD recordType; DWORD dateTime; DWORD transNum; DWORD cashierNum; WORD posNum; DWORD unitTicketNum; DWORD dwSerialNum; DWORD dwPlayerID; DWORD voidDateTime; // if !voidDateTime // if DB_REC_NORM, voidReason == additinoal pack unit ID // if DB_REC_ADDPACK voidReason == additinoal pack unit ID // if DB_REC_ADDPACK voidCashierNum == original unitTicket // if void ticket and is DB_REC_ADDPACK // relink master and additionals. // if void ticket is DB_REC_NORM and has additional packs // All additional packs are voided. #define unitLinkBase voidCashierNum DWORD voidCashierNum; #define unitLinkNext voidReason WORD voidReason; DWORD dwSurchargePacks; long lSurchargePrice; WORD numPacks; PACKENTRY pax[MAXXPAXX]; } PACKED DBSTRUCT; OK, that was the C++ version, here is my C# version. I didn't use an array for the PACKENTRY since C# doesn't allow declared arrays of another struct inside of itself. public struct PACKENTRY { public System.UInt32 packid; public long price; public long valPrice; public System.Byte byInvIndex; public System.Byte nothing; // filler to cause word alignment. public System.UInt16 numCards; public ushort packType; } public struct DBSTRUCT { public System.UInt32 crc32; public System.UInt16 recordType; public System.UInt32 dateTime; public System.UInt32 transNum; public System.UInt32 cashierNum; public System.UInt16 posNum; public System.UInt32 unitTicketNum; public System.UInt32 dwSerialNum; public System.UInt32 dwPlayerID; public System.UInt32 voidDateTime; public System.UInt32 voidCashierNum; public System.UInt16 voidReason; public System.UInt32 dwSurchargePacks; public long lSurchargePrice; public System.UInt16 numPacks; public PACKENTRY pax, pax2, pax3, pax4, pax5, pax6, pax7, pax8, pax9, pax10, pax11, pax12, pax13, pax14, pax15, pax16, pax17, pax18, pax19, pax20; public PACKENTRY pax21, pax22, pax23, pax24, pax25, pax26, pax27, pax28, pax29, pax30, pax31, pax32, pax33, pax34, pax35, pax36, pax37, pax38, pax39, pax40; public PACKENTRY pax41, pax42, pax43, pax44, pax45, pax46, pax47, pax48, pax49, pax50, pax51, pax52, pax53, pax54, pax55, pax56, pax57, pax58, pax59, pax60; public PACKENTRY pax61,pax62, pax63, pax64; } Thanks in advance for anyone willing to spend some time helping me with this issue!

4 Replies

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rmathis23y ago
Hey Mike, Thanks for your input. I had tried to use the MarshalAs attribute, but I couldn't figure out how to use it to create a fixed size array of structs rather than pointers. Since the size of data there is crucial, how do I make sure that the array is the perfect size instead of just an array of pointers? Thanks for suggesting [StructLayout(LayoutKind.Sequential)] . I believe that this is probably necessary for my struct to work in terms of extracting the data from the binary files I'm trying to extract.
jcity44423y ago
Also look at this link: thread on arrays and migrating -Mike
jcity44423y ago
I think you need to marshal the array instead of breaking it up as in: // Marshal as a C style array of Vertex, where the second (SizeParamIndex is zero-based) // parameter (size) contains the count of array elements. [DllImport ("SomeDll.dll")] public static extern void SomeUnsafeMethod( [MarshalAs(UnmanagedType.LPArray, SizeParamIndex=1)] Vertex[] data, long size ); Also you might want to include a layout attribute before the structure [StructLayout(LayoutKind.Sequential)] public struct MyStruct Hope this helps a little, -Mike
rmathis23y ago
Ok, one thing I already changed, was that I changed all the long values in my C# code to System.Int32 since I didn't realize that a long in C# is actually a 64 bit integer where as the long C++ is expecting is a 32 bit integer. I can't edit my post, so thus this... Thanks again