I have imported the kernel32 library so I have the
createMutex function available but I am not quite sure of the various parameters and return values.
This is classic Visual Basic, not Visual Basic.NET but I can probably work with either language in the form of an answer.
The VB code looks something like this:
hMutex = CreateMutex(ByVal 0&, 1, ByVal 0&)
The first parameter is a pointer to an
SECURITY_ATTRIBUTES structure. If you don't know what it is, you don't need it. Pass NULL (0).
The second parameter is
TRUE (non-zero, or 1) if the calling thread should take ownership of the mutex.
The third parameter is the mutex name and may be NULL (0), as shown. If you need a named mutex, pass the name (anything unique) in. Not sure whether the
VB wrapper marshals the length-prefixed
VB string type (
BSTR) over to a null-terminated Ascii/Unicode string if not, you'll need to do that and numerous examples are out there.
Here's the VB6 declarations for CreateMutex - I just copied them from the API viewer, which you should have as part of your VB6 installation. VB6 marshalls strings to null-terminated ANSI using the current code page.
Public Type SECURITY_ATTRIBUTES nLength As Long lpSecurityDescriptor As Long bInheritHandle As Long End Type Public Declare Function CreateMutex Lib "kernel32" Alias "CreateMutexA" _ (lpMutexAttributes As SECURITY_ATTRIBUTES, ByVal bInitialOwner As Long, _ ByVal lpName As String) As Long
Bear in mind that if you create a mutex from the VB6 IDE, the mutex belongs to the IDE and won't be destroyed when you stop running your program - only when you close the IDE.
Well, based on the documentation it looks like: