I have a strong recollection that when I did my P/Invoke work a few months ago, I ran into a problem where I had to look at the calling convention. So as I recall I think it does matter; it would stand to reason that you would have to P/Invoke the API using the same calling convention that the API is built to use. This may be the root of your problem. BTW, if the DLL is being built using a makefile you will want to look for the compiler switch /Gd for __cdecl and /Gz for __stdcall. I got this information from the following website: http://www.codeproject.com/cpp/calling_conventions_demystified.asp
I have tried googling this subject using the keywords "__cdecl pinvoke" and I got a lot of results; many of them contradicted my earlier statement that __cdecl is required. I also found this on the dotnet-cx board which sounds a lot like it answers your latest questions: http://discuss.develop.com/archives/wa.exe?A2=ind0406d&L=dotnet-cx&P=730 Unfortunately, you have reached the limit of my knowledge on the proper calling conventions. I don't want to give out any more bad information, except that I think this may be your problem. Your declarations look OK to me but again I am unfamiliar with what it takes to get a struct back as an out parameter. That would be the only other thing I could suggest you look into. A third thing to try, if you are familiar with C++, is to write a C++ test harness to simulate the calls that you are doing in C#, and make certain that you get the struct popuated with data. One of the earlier posters suggested that the DLL was failing internally before it allocated the struct, which could also be a cause of your problem. On Mon, 30 Apr 2007 08:44:21 -0700, Mont Rothstein <[EMAIL PROTECTED]> wrote: >Thanks for the additional info. > >I am compiling this DLL with VS 05 form the command line. It uses a >manually created make file and not a project. > >I didn't create the DLL, it is part of a package, which is why I am unclear >on some of this. > >I searched the directory where all of the source is kept for both __stdcall >and __decl with no hits on either. So I presume it uses whichever is >default for VS. > >I guess I should ask why it matters? Might the root of this problem be that >the wrong calling convention is used? Or might I need to change someone in >my C# code based on the calling convention? > >Thanks, >-Mont =================================== This list is hosted by DevelopMentor® http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
