Single Instance

Is it possible to check for an instance of a BB executable running and prevent another instance of the same program starting i.e. as in screensavers

; .lib "kernel32.dll"
; CreateMutex%(lpMutexAttributes%,bInitialOwner%,lpName$):"CreateMutexA" 
; GetLastError%():"GetLastError"

Const ERROR_ALREADY_EXISTS=183

CreateMutex(0,1,"My Program Instance") ; Mutex accessible to any program

If GetLastError() = ERROR_ALREADY_EXISTS Then
	Print "My program is already running" ; Shutdown
Else
	Print "This is the only instance of My Program" ; OK
EndIf

Many thanks for such a speedy response. I will give this a try ..

CreateMutex? GetLastError? Did you just make those commands up, or are they undocumented commands?

Getting error message - Function createmutex not found. Do I have to do something else to access kernal32.dll? I am very new to BB

The commented bit at the top is a userlib delaration. You need to put it in a file called "C:\program files\Blitz3D\userlibs\kernel32.decls" without the semicolons.

Many thanks people - all working well - just not used to such speedy responses in the Delphi programming world ! BB considerably better :-)

Sorry for not explaining earlier -- I was in a bit of a hurry! (It was "cut and paste" from my code archive.)

No problem - thanks again