Not sure if this will make a difference in your case, but it's worth a
shot.
I have my structs for unmanaged C++ calls declared as such:
Note, the LayoutKind parameter. Also should note the differences between
VC++ data types and C# data types.
long and int in VC++ both correspond to int in C#, etc.
[Guid( "..." ), StructLayout(LayoutKind.Sequential)]
public struct MyStruct{
public short Rows;
public short Cols;
public short Padding1;
public short Padding2;
[MarshalAs(UnmanagedType.ByValArray,SizeConst=128)]
public double[] Vals;
}
> -----Original Message-----
> From: Ron Young [mailto:[EMAIL PROTECTED]
> Sent: Tuesday, February 25, 2003 1:25 PM
> To: [EMAIL PROTECTED]
> Subject: [ADVANCED-DOTNET] Need help with a P/Invoke function
>
>
> Hello all,
>
> If someone could help me out with this, I'd appreciate it very much.
>
> I have this function signature in a Win32 .dll:
>
> S32 AIL_enumerate_filter_attributes( HPROVIDER filter,
> HINTENUM *next, RIB_INTERFACE_ENTRY *dest )
>
> the RIB_INTERFACE_ENTRY is a struct defined like so:
>
> struct RIB_INTERFACE_ENTRY
> {
> char const * entry_name;
> int type;
> int subtype;
> }
>
> I've attempted to define the struct in C# like so:
>
> public struct RIBInterfaceEntry
> {
> [MarshalAs( UnmanagedType.ByValTStr, SizeConst=128 )]
> public string name;
> int entrytype;
> int subtype
> }
>
> and wrapped the c++ method like so:
>
> [DllImport( "mss32.dll",
> EntryPoint="AIL_enumerate_filter_attributes" )]
> private static extern int EnumFilterAttributes( IntPtr
> filter, ref int next, ref RIBInterfaceEntry dest );
>
> and call it like:
>
> IntPtr next = 0;
>
> public RIBInterfaceEntry[] GetFilterAttributes( DigitalFilter filter )
> {
> while ( true )
> {
> RIBInterfaceEntry entry = new RIBInterfaceEntry();
> if ( EnumFilterAttributes( filter.Handle, ref next, ref
> entry ) == 0 ) break;
> // add the entry to an arraylist
> }
>
> // return arraylist.ToArray()
> }
>
> The DigitalFilter is another struct populated from another
> unmanaged call which holds all the available filters for a
> digital audio driver. When the app is run, and the
> GetFilterAttributes() method called, I don't get any run-time
> arrays, and stepping through the code shows the
> RIBInterfaceEntry[] array has a length of 2, but the
> individual properties of a specific entry don't seem right.
> The "Name" property has what appears to be a null terminator
> in it, and the 2 int properties are 0 (which is a valid value
> for the struct). But I was hoping to at least see a
> descriptive name of the entry, as in a C++ application I have
> that does basically the same thing (enumerates attributes,
> printf them to console window).
>
> Thanks again, and in advance for any advice.
>
> Ron
>
