How to create a .DLL file from a .C file ?

[sinaps]

Hi everybody

I'm looking for a method how to create a .DLL file from a .C file .That Dll file will be used to perform a board to measure voice quality accoding to the international standard named PESQ (perceptual evaluation of speech qualty) P.862.

Can anyone help to start dealing with Dlls and give some advices to avoid errors ?

thx

[Al.B]

Hi Sinaps,

The following document gives a walkthrough on creating a DLL in Visual Studio:

http://msdn.microsoft.com/en-us/library/ms235636(VS.80).aspx

Let me know if you have any questions regarding these steps!

Message Edited by Al B on 03-10-2009 12:54 PM

[Jervin Justin]

Hi sinaps,

You mention that you want to create a DLL from a .C file. Just to clarify, are you using C (.c file) or C++ (.cpp) to write your code?

Also, if you are using C++, are you using Visual Studio? (The reason I ask is because this forum is geared towards Measurement Studio, which is an add on to Microsoft Visual Studio).

That being said,

• If you are using C: National Instruments provides an ANSI C Application Development Environment called LabWindows/CVI which makes building dlls a snap. It has templates for DLLs and you can build them either as stdcall or cdecl dlls.
  Developer Zone Tutorial: Building a DLL with LabWindows/CVI 8.5 for use with LabVIEW 8.5
• If you are using Visual C++: Look at the link that Al provided earlier.
  MSDN: Walkthrough: Creating and Using a Dynamic Link Library
• If you aren't using CVI or Visual Studio, then really the best bet is to do a google search for "Create C DLL" or post or a forum for the appropriate environment that you are using.

Thanks!

Message Edited by Jervin_J on 03-14-2009 02:02 PM

[ozyMan]

Hi, I created DLL with C++ and it includes a function using NI::DataSocket.

I am trying to call that function from another C++ project and the function which is:

extern "C" __declspec(dllexport) double __cdecl Test()
{
   
   
   
       
    CNiDataSocket* socket = new CNiDataSocket; >>>>>Exception was thrown in this line
    socket->SetAccessMode(socket->ReadWriteAutoUpdate);
    socket->URL = "psp:\\localhost\Untitled Library 5\voltaj";
    socket->Connect();
    CNiDataSocketData data =  socket->GetData();
    double val = data.GetValue();
    delete socket;
    return val;

}

in dll returns exception : Microsoft C++ exception: NI::CNiOleException at memory location 0x0025f450.. 

Any idea?

Thanks a lot.

Ozan

[CharlesD]

I see that you have posted on another More applicable forum (http://forums.ni.com/ni/board/message?board.id=231&requireLogin=False&thread.id=3761).  You shopuld be able to get a better answer from that forum as this post is a little unrelated.