Programming Forums > Application Development > Visual Basic

cl0ckw0rk_ninj4 · Dec 7th, 2004, 6:18 PM

can someone tell me how to use the createmutex command to make a program runs its counterpart program after closing it

lets say
program1- does anything i want, and it gets closed
program2 - i want this one to know when the first one is closed and re open it

MrLee · Mar 15th, 2005, 10:23 AM

I can't say I am aware of the createmutex command but there are other ways for one application to 'know' when another has closed. Quite easily if they are both written by yourself. Please elaborate.

Rory · Mar 15th, 2005, 5:11 PM

Well, conventionally you use a mutex like this, though if you have two programs running in parallel you'd need to check for the mutex's existence periodically using a timer or a loop WITH A SLEEP STATEMENT IN IT (the number of BSOD's...). In fact you'd be better off using a hooked atom, checking the task list or actually actively notifying the program's counterpart through DDE, a window message or whatever.

(Toggle Plain Text)

Const ERROR_ALREADY_EXISTS = 183&
Private Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" (lpMutexAttributes As Any, ByVal bInitialOwner As Long, ByVal lpName As String) As Long
Private Declare Function ReleaseMutex Lib "kernel32" (ByVal hMutex As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long
Private Sub Form_Load()
    Dim hMutex As Long
    'Try to create a new Mutex
    hMutex = CreateMutex(ByVal 0&, 1, App.Title)
    'Did the mutex already exist?
    If (Err.LastDllError = ERROR_ALREADY_EXISTS) Then
        'Clean up
        ReleaseMutex hMutex
        CloseHandle hMutex
        'More than one instance detected
        MsgBox "More than one instance"
        End
    Else
        'form load code
    End If
End Sub

Mar 15th, 2005, 5:11 PM	#3
Rory Expert Programmer Join Date: Jan 2005 Location: London Posts: 542 Rep Power: 4	Well, conventionally you use a mutex like this, though if you have two programs running in parallel you'd need to check for the mutex's existence periodically using a timer or a loop WITH A SLEEP STATEMENT IN IT (the number of BSOD's...). In fact you'd be better off using a hooked atom, checking the task list or actually actively notifying the program's counterpart through DDE, a window message or whatever. (Toggle Plain Text) Const ERROR_ALREADY_EXISTS = 183& Private Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" (lpMutexAttributes As Any, ByVal bInitialOwner As Long, ByVal lpName As String) As Long Private Declare Function ReleaseMutex Lib "kernel32" (ByVal hMutex As Long) As Long Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long Private Sub Form_Load() Dim hMutex As Long 'Try to create a new Mutex hMutex = CreateMutex(ByVal 0&, 1, App.Title) 'Did the mutex already exist? If (Err.LastDllError = ERROR_ALREADY_EXISTS) Then 'Clean up ReleaseMutex hMutex CloseHandle hMutex 'More than one instance detected MsgBox "More than one instance" End Else 'form load code End If End Sub Const ERROR_ALREADY_EXISTS = 183& Private Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" (lpMutexAttributes As Any, ByVal bInitialOwner As Long, ByVal lpName As String) As Long Private Declare Function ReleaseMutex Lib "kernel32" (ByVal hMutex As Long) As Long Private Declare Function CloseHandle Lib "kernel32" (ByVal hObject As Long) As Long Private Sub Form_Load() Dim hMutex As Long 'Try to create a new Mutex hMutex = CreateMutex(ByVal 0&, 1, App.Title) 'Did the mutex already exist? If (Err.LastDllError = ERROR_ALREADY_EXISTS) Then 'Clean up ReleaseMutex hMutex CloseHandle hMutex 'More than one instance detected MsgBox "More than one instance" End Else 'form load code End If End Sub

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Dec 7th, 2004, 6:18 PM	#1
cl0ckw0rk_ninj4 Newbie Join Date: Dec 2004 Posts: 8 Rep Power: 0	can someone tell me how to use the createmutex command to make a program runs its counterpart program after closing it lets say program1- does anything i want, and it gets closed program2 - i want this one to know when the first one is closed and re open it

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Programming Forums > Application Development > Visual Basic

Createmutex Help???