Hmmm - is it possible that you want to achieve this so you can ensure there's only one person accessing a resource on the network somewhere? If it's a file, you could try locking the file appropriately...or you could do the job the safe and assurable way, and hide the resource behind a server, so the server is the only thing that can access it, giving you control again.

Hi, Thaks for your solution. :)

extern <string literal> specifies the external linkage that its name is visible outside the file in which it is defined, Microsoft C++ supports the strings "C" and "C++" in the string-literal field to specify the linkage convention of other languages, you can link to the function, if the linkage conventions are same.