'This code must be pasted into a module
'Set the project's startup object to 'Sub Main' (-> Project -> Project Properties -> General Tab -> Startup Object)
Public Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" (lpMutexAttributes As SECURITY_ATTRIBUTES, ByVal bInitialOwner As Long, ByVal lpName As String) As Long
Public Type SECURITY_ATTRIBUTES
nLength As Long
lpSecurityDescriptor As Long
bInheritHandle As Long
End Type
Public Const ERROR_ALREADY_EXISTS = 183&
Private Sub Main()
'KPD-Team 1999
'URL: http://www.allapi.net/
'E-Mail: KPDTeam@Allapi.net
' -> code by Raist Lin
Dim sa As SECURITY_ATTRIBUTES
sa.bInheritHandle = 1
sa.lpSecurityDescriptor = 0
sa.nLength = Len(sa)
'Try to create a new Mutex
Debug.Print CreateMutex(sa, 1, App.Title)
Debug.Print Err.LastDllError
'Check if the function was succesfull
If (Err.LastDllError = ERROR_ALREADY_EXISTS) Then
'More than one instance detected
MsgBox "More than one instance"
Else
'No other instance detected...
'Your program-load code here
End If
End Sub