Avoid two instances of the same app

[Nitin Agarwal]

Hi,

I am developing an application for my school project and would like to build
in a functionality, wherein whenever the application is run, it checks
whether another copy of the same application is running. If so, it would
pop an error.

Could anyone please guide me as to how can i do this.

Any help would be appreciated.

Thanks and regards,
Nitin

[Herfried K. Wagner [MVP]]

"Nitin Agarwal" <na******@bu.edu> scripsit:

I am developing an application for my school project and would like to build
in a functionality, wherein whenever the application is run, it checks
whether another copy of the same application is running. If so, it would
pop an error.

\\\
Public Shared Function PrevInstance() As Process
Dim c As Process = Process.GetCurrentProcess()
Dim p As Process
For Each p In Process.GetProcessesByName(c.ProcessName)
If p.Id <> c.Id Then
If p.MainModule.FileName = c.MainModule.FileName Then
Return p
End If
End If
Next p
Return Nothing
End Function
///

- or -

\\\
Imports System.Threading
..
..
..
Dim m As Mutex = _
New Mutex(False, "{11C92606-65D9-4df2-9AEA-B6A4DA91BCE2}")
If m.WaitOne(10, False) Then
Application.Run(New Form1())
m.ReleaseMutex()
Else
MessageBox.Show("Application already running!")
End If
///

--
Herfried K. Wagner
MVP · VB Classic, VB.NET
<http://www.mvps.org/dotnet>

[Nitin Agarwal]

Great! thanks so much!

"Herfried K. Wagner [MVP]" <hi*******@m.gmx.at> wrote in message
news:bl**********@activevb.de...

"Nitin Agarwal" <na******@bu.edu> scripsit:

I am developing an application for my school project and would like to build in a functionality, wherein whenever the application is run, it checks
whether another copy of the same application is running. If so, it would pop an error.

\\\
Public Shared Function PrevInstance() As Process
Dim c As Process = Process.GetCurrentProcess()
Dim p As Process
For Each p In Process.GetProcessesByName(c.ProcessName)
If p.Id <> c.Id Then
If p.MainModule.FileName = c.MainModule.FileName Then
Return p
End If
End If
Next p
Return Nothing
End Function
///

- or -

\\\
Imports System.Threading
.
.
.
Dim m As Mutex = _
New Mutex(False, "{11C92606-65D9-4df2-9AEA-B6A4DA91BCE2}")
If m.WaitOne(10, False) Then
Application.Run(New Form1())
m.ReleaseMutex()
Else
MessageBox.Show("Application already running!")
End If
///

--
Herfried K. Wagner
MVP · VB Classic, VB.NET
<http://www.mvps.org/dotnet>

[K. Shier]

two questions:

#1 - where did you get the CLSID?

#2 - how would you make it so instead of showing a dialog, it activates the
running instance?

Dim m As Mutex = _
New Mutex(False, "{11C92606-65D9-4df2-9AEA-B6A4DA91BCE2}")
If m.WaitOne(10, False) Then
Application.Run(New Form1())
m.ReleaseMutex()
Else
MessageBox.Show("Application already running!")
End If
///

--
Herfried K. Wagner
MVP · VB Classic, VB.NET
<http://www.mvps.org/dotnet>