How to check if program is already running

[SkYWAGz]

I only want my application to run once at a time. If it's already running and the user runs it again, it should close automaticly. Basicly the program should get it's name and check if it's running as a task. If so, it should quit.

[tath]

you can create global synchronization point (like event or mutex) which is set with main instance of the program, and other instances check if it is set or not. ie.:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms633559%28v=vs.85%29.aspx

hPrevInstance [in]

Type: HINSTANCE

A handle to the previous instance of the application. This parameter is always NULL. If you need to detect whether another instance already exists, create a uniquely named mutex using the CreateMutex function. CreateMutex will succeed even if the mutex already exists, but the function will return ERROR_ALREADY_EXISTS. This indicates that another instance of your application exists, because it created the mutex first [...]