It's really just sort of a weird optimization trick. You shouldn't use it in a regular program unless you have a very, very good reason. The fact that it works

It's really just sort of a weird optimization trick. You shouldn't use it in a regular program unless you have a very, very good reason. The fact that it works at all (ie, that you can inject the start of a loop into the middle of a switch statement) is surprising to most people. I've shown this to people who've been programming since before I was born, and they struggled to understand it at first since they had no idea that it was syntactically possible to do that -- it's not the kind of thing you normally think of when writing a program in C. If you know an assembly language and how C maps onto assembly, it's pretty easy to make sense of though, after you get over the shock of the syntax permitting this particular construction.