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Re: About =?UNKNOWN?Q?DLL=B4s?= again



     Hi Ismael,
     
     Thank you very much for your job, for the first time I can build a 
     DLL.
     
     cheers
     
     pascal


______________________________ Reply Separator _________________________________
Subject: About =?UNKNOWN?Q?DLL=B4s?= again
Author:  ismaelj@hotmail.com at INTERNET
Date:    17/04/1997 14:43


About the DLL's that don't work:
     
  Few days ago I posted a procedure to make DLL. This procedure was based
on my own experience, experience that I want to share with the group, because 
for me work great, it will do so for others. In the other hand , I4m not a 
Windows 'guru', I only try to do my best. Anyway, here are some answers
to your questions.
     
Matt Calder <calder@stat.colostate.edu> wrote
     
> I find that I can load the dll during the WinMain procedure, and 
> in some parts of the WinProc (Main window procedure). The library
> will load if I am in the message handler for WM_CREATE or WM_PAINT, 
> but not in the message handler for WM_COMMAND! When I say message
 ...
> In this configuration the dll is loaded, if the LoadLibraryEx() 
> call is moved into the WM_COMMAND portion it will not load. I
> don't understand why, if I use a dll built with MSVC it works 
> fine. Any help would be very much appreciated.
     
  I've tested myself this and I4ve found the same problem that you, that
the program failed to load the DLL, but it4s a problem of the program generated 
by the compiler. To prove this, I compiled the DLL folowing the procedure I 
posted (using the cygnus tools), and then I make 3 compilings of the test 
program
(similar to the one you posted) one with the cygnus package,
other with the Minimalist (Mingw32) package, and other with Borland C++ 5.0. 
The programs generated by gcc failed to load the DLL, but the one compiled 
with Borland did it's work independently of where in the program I put
the LoadLibrary() call (that it's well-formed as long as I know).
     
  For me, that testing shows that the procedure to generate the DLL4s
work, but something fails within gcc, or maybe it4s only a lack of the 
right option in the command line... I don4t know what it is.
     
HARBAUGH@FCRFV1.NCIFCRF.GOV wrote:
     
> Ismael, your example worked great, but I still have a problem because 
> I need to pass arguments.  Whenever I try to write a function that
> passes arguments, the linker complains as follows: 
>
> (d:\CYGNUS\H-I386~1\BIN\ld.exe 1304) In cygwin_except_handler 
> (d:\CYGNUS\H-I386~1\BIN\ld.exe 1304) Exception trapped!
> (d:\CYGNUS\H-I386~1\BIN\ld.exe 1304) exception C0000005 at 438238
     
HARBAUGH@FCRFV1.NCIFCRF.GOV wrote in other message:
     
> I figured out one way to stop the errors I wrote about in my 
> last message; I added a MessageBox call in the DllMain
> function, just as you did.  THEN THE DLL WORKED.
> Unfortunately, I really must get rid of that MessageBox call.
     
  I don4t know what is wrong here. Again, I made a modification on my
example for a function passing values, and make 3 compilations and got 
this: it works when I call the funcion linking with the Dll, and don4t 
works when I call the function via LoadLibrary(), no matter if DLLMain() 
have or not a MessageBox() call. Here are the test results:
     
Mydll.dll : Always build with gcc using cygnus tools and folowing the
            procedure posted
App A     : Test example loading the DLL via LoadLibrary and calling
            foof with GetProcAddress()
App B     : Test example linking with mydll.a and calling directly foof
     
Envoriment              | cygnus | mingw32 | borland | 
------------------------|--------|---------|---------| 
void foof()     & App A |   Y    |    Y    |    Y    | 
int foof(LPSTR) & App A |   N    |    Y    |    Y    | 
void foof()     & App B |   Y    |    Y    |    Y    | 
int foof(LPSTR) & App B |   Y    |    Y    |    Y    | 
------------------------------------------------------
     
HARBAUGH@FCRFV1.NCIFCRF.GOV wrote in other message:
     
> I realize I must be doing something wrong, but I have no idea what it could 
be.
> Ultimately I want to be able to pass values back to a Visual Basic calling 
> procedure.  If you can help me, please let me know.
     
  About this, I have heard something like cygnus-produced DLL's can4t
be loaded by other DLL, and as far as I know, the VB code is a DLL...
     
  So, I trust on may procedure: the DLLs work OK, but not the programs
that must load them. Any clue about this ?
     
        Ismael Jurado
        Ismaelj@hotmail.com
     
     
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