Hello everybody,
I'm currently trying to understand how marshaling can use used for accessing
Win32 API functions as well as custom C/C++ code we design which exposes
functions the same way as the Win32 API.
I figured how to use strings... No problem there, there was a couple undred
examples on the net. I have yet to find how to do the same with an array of
integers for example... Here's my test code :
C strucure I'm trying to match :
typedef struct {
char name[200];
long id;
double a;
bool b;
char c;
short d[100];
} struct1;
Here's the VB structure in it's current (non working) state :
<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi, Pack:=4)> _
Private Structure struct1
<VBFixedString(200), MarshalAs(UnmanagedType.ByValTStr, SizeConst:=200)>
_
Public name As String
Public id As Int32
Public a As Double
Public b As Boolean
Public c As Char
<VBFixedArray(100), MarshalAs(UnmanagedType.I2, SizeConst:=100)> _
Public d() As Int16
End Structure
Two different problems occur using this definition. First, the
Marshall.SizeOf() call on an instance of the structure gives me this msg:
An unhandled exception of type 'System.ArgumentException' occurred in
WindowsApplication2.exe
Additional information: Le type struct1 ne peut pas être marshalé comme une
structure non managée ; il n'est pas possible de calculer une taille ou un
offset.
Rough traduction from french :
The struct1 type cannot be marshalled as an unmanaged type ; it is
impossible to calculate a size or an offet.
I don't quite understand why I get this message, or what it means for that
matter.
The second problem is that if I modify the member "d" from my C DLL, I get
the following error :
An unhandled exception of type 'System.TypeLoadException' occurred in
WindowsApplication2.exe
Additional information: Impossible de marshaler le champ d du type struct1 :
ce type ne peut pas être marshalé comme un champ structuré.
Rough traduction from french :
Unable to marshall the d "field" of struct1 : this type cannot be marshaled
as a structured "field".
I've been looking over MSDN and the internet all morning and I still can't
figure how to make this work...
Any help would be appreciated!
Alex.
