Single Application Run

[Tom Rogers]

How do I make it so that once my application (.exe) is running, if the user
tries to run a second instance of the program, it is not allowed.

I want my program to be able to have only one instance of it running,
period.

Thx,

-Tom

[Karl E. Peterson]

Re: Single Application Run

Tom Rogers wrote:

How do I make it so that once my application (.exe) is running, if
the user tries to run a second instance of the program, it is not
allowed.
>
I want my program to be able to have only one instance of it running,
period.

There are quite a number of ways. The simplest is something like this:

Sub Main
If App.PrevInstanc e Then Exit Sub
...

If you know the caption of your app, you can enhance this like:

Sub Main
If App.PrevInstanc e Then
AppActivate MyCaption
Exit Sub
End If
...

For more ideas, see http://vb.mvps.org/samples/PrevInst
--

[Henning]

Re: Single Application Run

Google is a good friend :)
From VBForums-ClassicVB by dee-u.

Method 1: You can read the PrevInstance property of the App object, if the
value of this is True then another instance of the application is already
running.

If your program starts with Sub Main, you can use this code to exit the
program if another copy is already running:
visual basic
code:-----------------------------------------------------------------------
-------'in sub main...
If App.PrevInstanc e = True Then
MsgBox "Already running...."
Exit Sub
End If
----------------------------------------------------------------------------
--For forms you need an extra piece of code to also close the form, the
following code should be placed in Form_load:
visual basic
code:-----------------------------------------------------------------------
-------'in form_load...
If App.PrevInstanc e = True Then
MsgBox "Already running...."
Unload Me
Exit Sub
End If
----------------------------------------------------------------------------
--

Method 2: You can use the FindWindow API to search for open windows with
your form caption.

Note that for this to work you must know the exact title to find, so if you
change your window title within your program

(such as adding a file name, like Notepad does) then this will fail. Also,
if other running programs have the same caption,

your program may not run at all.

visual basic
code:-----------------------------------------------------------------------
-------
Option Explicit

Private Declare Function FindWindow Lib "user32" Alias "FindWindow A" (ByVal
lpClassName As String, ByVal lpWindowName As String) As Long

Public Sub Main()
Dim m_hWnd As Long

'Change Form1 to your form Caption.
m_hWnd = FindWindow(vbNu llString, "Form1")
If m_hWnd 0 Then
MsgBox "Program " & App.Title & " is already running..."
Exit Sub
End If

'Change Form1 to your form name.
Form1.Show
End Sub
/Henning"Tom Rogers" <jeditom@NO_SPA Mtwcny.rr.comsk rev i meddelandet
news:6Nxtg.8536 4$3B.44128@twis ter.nyroc.rr.co m...

How do I make it so that once my application (.exe) is running, if the

user

tries to run a second instance of the program, it is not allowed.
>
I want my program to be able to have only one instance of it running,
period.
>
Thx,
>
-Tom
>
>
>

[Henning]

Re: Single Application Run

Untested

http://www.planetsourcecode.com/vb/scripts/ShowCode.asp?txtCodeId=65732&lngWId=1

/Henning

"Tom Rogers" <jeditom@NO_SPA Mtwcny.rr.comsk rev i meddelandet
news:6Nxtg.8536 4$3B.44128@twis ter.nyroc.rr.co m...

How do I make it so that once my application (.exe) is running, if the

user

tries to run a second instance of the program, it is not allowed.
>
I want my program to be able to have only one instance of it running,
period.
>
Thx,
>
-Tom
>
>
>