Re: Sending a buffer to C++ DLL
- From: Jeroen Mostert <jmostert@xxxxxxxxx>
- Date: Tue, 29 Jan 2008 21:34:01 +0100
dollardan@xxxxxxxxxxx wrote:
I've read through the forum and I couldn't get my code to run with anyTwo important things missing here: you must inform the marshaler that the string is not Unicode (as I presume it's not), and that the bool you're returning is a C++ bool rather than a Win32 BOOL.
of the solution I found there.
My project has 3 main components:
Legacy.dll - unmanaged C++
DotNet.dll - C# Class Library. Interop for the Legacy DLL
TestApp.exe
My Problem:
I'm trying to send a buffer to the DotNet.dll from the TestApp for it
to forward to the Legacy.dll. I an having trouble writing the DLL and
calling its methods.
The buffer only contains data that I want the Legacy DLL to read.
That's it. It seems simple enough to do, but I keep tripping the
AccessViolationException:
Attempted to read or write protected memory. This is often an
indication that other memory is corrupt.
Legacy DLL:
bool SetData( UCHAR *buffer, int size);
DotNet DLL:
public static class DotNet
{
[DllImport("Legacy.dll")]
public static extern bool SetData(String buffer, int size);
}
[DllImport("Legacy.dll", CharSet = CharSet.Ansi)]
[return: MarshalAs(UnmanagedType.U1)]
public static extern bool SetData(string buffer, int size);
With these changes, it should just work:
string input = "Hello there!";
SetData(input, input.Length);
Note that it's vitally important that the string you pass to SetData is not modified. Otherwise, you need to use StringBuilder to marshal the data across instead.
--
J.
.
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