Problem with Unions

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

BxB - 06 Oct 2005 17:08 GMT

Hello I need help to interop this structure in C# to make an wrapper for the
"InstallApplication" method:

typedef union _INSTALLSPEC {
struct {
WCHAR* Name;
GUID GPOId;
} AppName;
WCHAR* FileExt;
WCHAR* Reserved1;
struct {
GUID Reserved1;
DWORD Reserved2;
} Reserved2;
} INSTALLSPEC;

Unions are hard to interop here, any Idea?

ref =>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/policy/policy/i
nstallspec_union.asp

Thanks

BxB

Reply to this Message

Robert Jordan - 06 Oct 2005 18:11 GMT

> Hello I need help to interop this structure in C# to make an wrapper for the
> "InstallApplication" method:
[quoted text clipped - 13 lines]
>
> Unions are hard to interop here, any Idea?

They are not. However, INSTALLSPEC is a little bit hard to deal with.

Untested:

[StructLayout(LayoutKind.Explicit)]
public struct INSTALLSPEC
{
[FieldOffset(0)] [MarshalAs(UnmanagedType.LPWStr)]
public string Name;

[FieldOffset(4)][MarshalAs(UnmanagedType.ByValArray, SizeConst=16)]
public byte[] GPOid;

[FieldOffset(0)] public string FileExt;

// GPOid accessor
public Guid Guid {
get { return new Guid(GPOid); }
set { GPOid = value.ToByteArray(); }
}
}

Though incomplete, this still works, because you don't need
the reserved fields that take the same place or less that
the other fields.

Rob

Reply to this Message

Problem with Unions

Free Magazines