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Start application once

Posted on 1998-09-12
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Last Modified: 2010-04-06
How can I prevent my application from being started twice? In Delphi 1 I could use the variable HPrevInst.

It's an MDI-application with various captions.
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Question by:detempel
3 Comments
 
LVL 3

Expert Comment

by:Matvey
ID: 1339559
Several components exist, like this one:

http://bes.trendline.co.il/torry/vcl/system/bjustone.zip
"A component that enables only one unique instance of an application at each time."

There are several more on

http://bes.trendline.co.il/torry/system.htm, system2.htm, system3.htm, system4.htm

--Matvey
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Accepted Solution

by:
viktornet earned 50 total points
ID: 1339560
Here is some code ;-)
----------
interface
uses Windows;
ResourceString
        AppCantStart = 'App is already running. Can not start another copy.';
        AppTitle = 'Just an App';
implementation
const
        TEN_SECONDS = 10000;
var
        MutexHandle : integer;
initialization
   MutexHandle := CreateMutex(Nil, False, 'DME Local Server Mutex.');
   if WaitForSingleObject(MutexHandle, TEN_SECONDS) <> WAIT_OBJECT_0
then
   begin
      MutexHandle := -1;
      Messagebox(0, PChar(RSCantStart), PChar(RSTitle), MB_OK);
      Halt;
   end;

finalization
        if MutexHandle <> -1 then
        ReleaseMutex(MutexHandle);
end.
--------------
Regards,
Viktor Ivanov
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Author Comment

by:detempel
ID: 1339561
Adjusted points to 50
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