> Hi there,
>
> I am currently translating a VB 6.0 application to .NET and have the
> following problem:
>
> The data structure I need to pass to a DLL function call has a structure
> variable inside its structure:
>
>     Private Structure CstData_type
>         Dim Cst_AZ As DbLong
>         Dim Cst_DECKS As DbLong
>         Dim Cst_LUZ As DbSingle
>         Dim Cst_ZoneLen As ZoneSingleArray
>     End Structure
>
> where
>
>     Private Structure ZoneSingleArray
>         Dim ZoneArr(20) As DbSingle
>     End Structure
>
> The Function call of the DLL is declared as
>
>     Private Declare Function ShPlcDb_Rd_Data
>        Lib "D:\ShPLCDb\ErShPlcDb.dll"
>        Alias "_ShPlcDb_Rd_Data@24"
>              (ByVal nSubSysNode As Integer,
>               ByVal nDataType As Integer,
>               ByVal nDataIdx As Integer,
>               ByVal nDataCnt As Integer,
>               ByRef pData As "Any",
>               ByVal nDataLen As Integer) As Integer
>
> Note the 5th parameter in the function call (pData) is declared
> originally as Any (VB6.0).
>
> Now, if I use the directive <StructLayout(LayoutKind.Sequential)> to
> declare the struct and change the type of the 5th parameter in the
> function call from Any to CstData_type, the function call works fine up
> until the last variable in the struct Cst_ZoneLen. If I leave it out, it
> works. If I put the last variable in the declaration, I get the error
> message:
>
> System.TypeLoadException
> Additional information: Can not marshal field Cst_ZoneLen of type
> CstData_type: The type definition of this field has no layout
> information.
>
> I have tried to declare the Structure ZoneSingleArray with
> <StructLayout(LayoutKind.Sequential)> as well, but that didn't do the
> trick. I get the same error.
>
> Question: How should I declare the data structure so it works with my
> DLL?
>
> Looking forward to any suggestions!
>
> Falko
>
> *** Sent via Developersdex http://www.developersdex.com ***