[DUG] Dll issue

[Rohit Gupta]

I dont know about widestrings, but ansistrings can be a problem with 
dlls.  Also note that if written in Delphi you have to handle all 
exceptions inside the dll.... as the exception itself uses ansistring.

Robert martin wrote:
> Hi again
>
> Further to my previous email I want to check that I have this right.  
> I think I am doing something wrong in relation to passing variables.
>
> My dll Call is defined as
>
>  TRunEFTPOS = Function(var Amount, CardType, ResCode: WideString; 
> Account, MercRef, TransRef, HeaderLine, FooterLine : WideString) : 
> Boolean;
>
> Note is users var parameters.
>
>
> This is my test calling code
>
> var
>    RunIt           : TRunEFTPOS;
>    EFTPOSHandle    : THandle;
>    ARes            : WideString;
>    CardType        : WideString;
>    iRes            : Integer;
>    Amt             : Extended;
>    TestAmt         : WideString;
>    Authorised      : Boolean;
> begin
>  inherited;
>    //RUN DLL
>
>    CardType := '';
>    Amt :=  10.95;
>    TestAmt := FloatToStr(Amt);
>
>    EFTPOSHandle := LoadLibrary('EftPos.dll');
>    if (EFTPOSHandle <> 0) then begin
>        try
>            @RunIt := GetProcAddress(EFTPOSHandle, 'RunIt');
>
>            if (@RunIt <> nil) then begin
>                Authorised := RunIt(TestAmt, CardType, ARes, '1', '1', 
> '12345' , 'Test eftpos', 'Test');
>                iRes := StrToIntDef(ARes, -1);
>
>                if (Authorised = True) then begin
>
>                    ShowMessage(TestAmt);
>                end;
>            end;
>        finally
>            FreeLibrary(EFTPOSHandle);
>        end;
>    end;
>
>
>
>
> Could passing var parameters be the root cause of my problem?  (This 
> Dll was working fine previously)
>
> Also the calling app has Sharemem in the uses clause but the dll does 
> not.  Adding it to the dll causes an av 'after' running the dll in the 
> test app, the main app still dies at the start.
>
> Any comments would be appreciated.
>
>
>
>
> Rob Martin
> Software Engineer
>
> phone +64 03 377 0495
> fax   +64 03 377 0496
> web www.chreos.com
>
> Wild Software Ltd
>
>
>
> Robert martin wrote:
>> Hi
>>
>> I have been using a (home made) DLL to interface between our app and 
>> an eftpos systems ActiveX control.  All worked well until we updated 
>> their software.  Now my app blows away when I try to create the 
>> ActiveX (in the dll).  However after much testing I have discovered 
>> if I call the dll from behind a TAdvGlowButton (fancy glowing button) 
>> it works ! but I get an error in GDIPlus.dll after the first time.
>>
>> It seems to be some sort of issue between the dlls being used 
>> (GDIPlus.dll and eftpos.Dll
>>
>> Any ideas ?
>>
>>
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-- 
*Rohit Gupta*
* B.E. Elec.   M.E.   Mem IEEE    Associate IEE*
*Technical Manager*
*Computer Fanatics Limited*
** 
*Tel*     +64 9 4892280
*Fax*    +64 9 4892290
*Email  *rohit at cfl.co.nz <mailto:rohit at cfl.co.nz>**
*Web    *www.cfl.co.nz <http://www.cfl.co.nz/>
 
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