LoadLibrary problem

LoadLibrary problem

[Szymon Guz]

Hi,
I keep on trying to load a dll library using for that the WinApi 
function LoadLibrary.

<CODE>
with Interfaces.C;


procedure Lib is 
   package C renames Interfaces.C;
   use type C.Char_Array;

   function LoadLib (
         Library : in     C.Char_Array ) 
     return C.Int; 

   pragma Import(C,LoadLib,"LoadLibrary");

   Handle : C.Int;  



begin
   Handle:=LoadLib("a");
end Lib;
</CODE>

I still get the linker error: 
./Lib.o(.text+0x12):Lib.adb: undefined reference to `LoadLibrary'

Where is the mistake ?

I'm using gnat and AdaGIDE under Windows98.

-- 
Szymon Guz

Re: LoadLibrary problem

[David C. Hoos]

The mistake is that you need to tell the linker where to find the file
that contains the "LoadLibrary" object code.

If you use the Win32ada library, it's found in libole32.a.

What's more, instead of writing your own interface, you can use
the imports provided in the win32-winbase.ads file, viz.:

    pragma Import(Stdcall, LoadLibraryA, "LoadLibraryA");         -- 
winbase.h:3619
    pragma Import(Stdcall, LoadLibraryW, "LoadLibraryW");         -- 
winbase.h:3625
    pragma Import(Stdcall, LoadLibraryExA, "LoadLibraryExA");     -- 
winbase.h:3637
    pragma Import(Stdcall, LoadLibraryExW, "LoadLibraryExW");     -- 
winbase.h:3645

Also, note that the C calling convention is not the proper convention for
use with
Win32 libraries.

I hope this helps

"Szymon Guz" <alpha@SMIECI_WON.skynet.org.pl> wrote in message
news:Xns946DEEAEE1E18Szymon.Guz@193.110.122.80...
> Hi,
> I keep on trying to load a dll library using for that the WinApi
> function LoadLibrary.
>
> <CODE>
> with Interfaces.C;
>
>
> procedure Lib is
>    package C renames Interfaces.C;
>    use type C.Char_Array;
>
>    function LoadLib (
>          Library : in     C.Char_Array )
>      return C.Int;
>
>    pragma Import(C,LoadLib,"LoadLibrary");
>
>    Handle : C.Int;
>
>
>
> begin
>    Handle:=LoadLib("a");
> end Lib;
> </CODE>
>
> I still get the linker error:
> ./Lib.o(.text+0x12):Lib.adb: undefined reference to `LoadLibrary'
>
> Where is the mistake ?
>
> I'm using gnat and AdaGIDE under Windows98.
>
> -- 
> Szymon Guz
> _______________________________________________
> comp.lang.ada mailing list
> comp.lang.ada@ada-france.org
> http://www.ada-france.org/mailman/listinfo/comp.lang.ada
>
>

Re: LoadLibrary problem

[tmoran]

>What's more, instead of writing your own interface, you can use
>the imports provided in the win32-winbase.ads file, viz.:
>
>    pragma Import(Stdcall, LoadLibraryA, "LoadLibraryA");         --
>winbase.h:3619
> ...
>Also, note that the C calling convention is not the proper convention for
>use with Win32 libraries.

Or you could use Claw:
package CLAW.DLL is ...
    type DLL_Type is new Ada.Finalization.Controlled with private;
    procedure Load (DLL_Object: in out DLL_Type;
                    DLL_File:   in String);
    ...
and let it worry about things like Ada->C strings, proper finalization of
the handle, and StdCall vs C.

Re: LoadLibrary problem

[Szymon Guz]

David C. Hoos wrote:
> The mistake is that you need to tell the linker where to find the file
> that contains the "LoadLibrary" object code.
> 
> If you use the Win32ada library, it's found in libole32.a.
> 
> What's more, instead of writing your own interface, you can use
> the imports provided in the win32-winbase.ads file, viz.:
> 
>     pragma Import(Stdcall, LoadLibraryA, "LoadLibraryA");         -- 
> winbase.h:3619
>     pragma Import(Stdcall, LoadLibraryW, "LoadLibraryW");         -- 
> winbase.h:3625
>     pragma Import(Stdcall, LoadLibraryExA, "LoadLibraryExA");     -- 
> winbase.h:3637
>     pragma Import(Stdcall, LoadLibraryExW, "LoadLibraryExW");     -- 
> winbase.h:3645
> 
> Also, note that the C calling convention is not the proper convention for
> use with
> Win32 libraries.
> 
> I hope this helps
> 

yea, that helped a lot
tnx