Mutex

[TheBao]

I am trying to create a Mutex object using the API:

Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" (lpMutexAttributes As SECURITY_ATTRIBUTES, ByVal bInitialOwner As Long, ByVal lpName As String) As Long

So far without success. Have you done it before. Please help.

Regards.

[Vlatko]

Here is an example of how to use than function:

'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()
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