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How can I get error number from exception

Posted on 1998-08-10
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Last Modified: 2010-04-04
Earler with pascal the error code number was geven by IOResult function.
But in delphi with exception handling how can I get the last error number for example I/O errors code.
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Question by:Motaz
  • 2
4 Comments
 
LVL 10

Expert Comment

by:viktornet
ID: 1361828
If I'm getting you right here is an example..otherwise give some more details please....thanx

var

  F: file of Byte;
begin
  if OpenDialog1.Execute then begin
    AssignFile(F, OpenDialog1.FileName);
    {$I-}
    Reset(F);
    {$I+}
    if IOResult = 0 then
      MessageDlg('File size in bytes: ' + IntToStr(FileSize(F)),
        mtInformation, [mbOk], 0);
    else
      MessageDlg('File access error', mtWarning, [mbOk], 0);
  end;
end;

Regards,
Viktor Ivanov
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Accepted Solution

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ZifNab earned 10 total points
ID: 1361829
Hi Motaz,

 if you use exceptions for your IO control then the exceptions you get are of type EInOutError :

type
 EInOutError = class(Exception)
   ErrorCode: Integer;
 end;

So the ErrorCode give the same result as IOResult in early pascal days (or still in delphi for compatibility?)

try
 ...
except
 on E: Exception do showMessage('ErrorCode: ', E.ErrorCode);
end;

Zif.
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LVL 7

Author Comment

by:Motaz
ID: 1361830
Thanks ZifNab, you are a porfull Delphi programmer. I hope I become like you. I search for this error number for a long time. Thanks again for your help. But there is some bugs in your code but it isn't important, that is the correction :

procedure TForm1.Button1Click(Sender: TObject);
var
     f:file;
begin
  try
    AssignFile(f,'NonExist.err');
    Reset(f);
    closefile(f);
  except
  on E: EinoutError do
    showMessage('ErrorCode: '+IntToStr(E.ErrorCode));
  end; (*** end try ***)

end;

Motaz.
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LVL 8

Expert Comment

by:ZifNab
ID: 1361831
Motaz, ok correct, there is a bug! Thanks for letting me know. I did it by hand, so there was a possibility for a bug. Zif.
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