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problem with DriveComboBox

Posted on 1999-01-18
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Last Modified: 2008-02-01

Hi experts,

I have a form with a DriveComboBox in my program. This ComboBox displays all drives on my PC (harddisk,floppy drive,cd-rom drive,
JAZ-drive)

If I try to select a file from the harddisk, everthing works perfectly. However if I try to select a file from
floppy disk/CD-ROM/JAZ-drive, this will cause a run-time error, if there is no medium inserted in the
floppy disk/CD-ROM/JAZ-drive.
(Delphi says: "exception of class ElnOutError. I/O error 21.

How can I work around this problem? Can you please show me a sample source code which fixes this problem?

With kind regards

Mathes

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Question by:mathes
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5 Comments
 
LVL 1

Expert Comment

by:martin_g
ID: 1362355
It's not great but will probably work!

Include an exception handler such as

procedure TForm1.DriveComboBox1Change(Sender: TObject);
begin
try

except on EINOUTError do
  ShowMessage('Drive not available');
  end;
end;
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LVL 3

Accepted Solution

by:
philipleighs earned 80 total points
ID: 1362356
Here is one way of dealing with this.

Make sure that the DirList property is empty.
In the Drive combo change event type this:

procedure TForm1.DriveComboBox1Change(Sender: TObject);
  begin
    if DiskFree(Ord(UpCase(DriveComboBox1.Drive)) - Ord('A') + 1) <> -1 then
      begin
        //This drive is ready.
        DirectoryListBox1.Drive := DriveComboBox1.Drive;
      end
    else
      begin
        //The drive is not ready, so set the drive back to
        //what we started with.
        ShowMessage('drive not ready');
        DriveComboBox1.Drive := DirectoryListBox1.Drive;
      end;
  end;

//DiskFree is used to determine if the drive is ready. It returns -1 if not.

Cheers,
Phil.

0
 

Author Comment

by:mathes
ID: 1362357

Dear Phil,

thank you for your feedback. Can you please tell me, how I can empty
the DirList property. Whenever I tried your routine in my sample code, the
DirListbox was never empty and therefore I got a runtime error.

With kind regards

Mathes


 

0
 
LVL 3

Expert Comment

by:philipleighs
ID: 1362358
Real easy, in the designer click the DriveCombo component, open object inspector, click the DirList property and press Delete, Enter. Now run the program!

Regards,
Phil.

0
 

Author Comment

by:mathes
ID: 1362359
Thank you for your help. This is exactly what I was looking for.

With kind regards

Mathes
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