Can't blame IBM either. I had to replace pthread_getthreadid_np() (in the IBM example code) with pthread_self() because Cygwin doesn't support/have pthread_getthreadid_np(). And the IBM docs say pthread_getthreadid_np() returns "a structure containing the hi and low order 4 bytes of the 64bit ID". The 2 "%.8x" would make sense. ---Jan On Fri, Jul 29, 2011 at 1:16 PM, Jan Chludzinski <jan.chludzinski@xxxxxxxxx> wrote: > Thanks! > > This is an example (from IBM) I cut-and-paste into Emacs to better > understand pthread_once(...). Didn't notice the two "%.8x" in > printf(). > > Thanks again, Jan >