Just to clarify anotherone a little, it is called (according to the ascii manpage) a C program escape. The null escape corresponds to the ASCII value 0, in other words '/0' == 0 for those rare few of you coders that aren't ASCII savvy (unlike danthaman). Interesting side note: null is the default contents of the memory addresses of unassigned pointers. Anyhow, trying to write to memory address null results in a Segfault or GPF (or some weird bomb thing for you Mac users). Reading a character array as anotherone described results pretty much in the same thing. No worries though, by default ( at least on my linux box) every fourth character or so is a null in an array, and C's pretty good at sticking them on when it needs to.