This is not actually a virus but a practical joke. It will make your victim believe that his system is under seize and is infected. Remember you need to compile it only (.ie click on compile option ) and not run it(i.e click on run option). This will generate the .EXE file.
Even though this is just a prank just be careful to whom you spread it as you could still get into minor trouble @ viruswriting.blogspot.com/2008/02/virus-code-in-cc.html