On Fri, 18 Sep 2020, Paul Eggert wrote: > On 9/18/20 7:34 AM, Florian Weimer via Libc-alpha wrote: > > the length modifier for printf and scanf is z, commently used as > > %zu or %zx (%zd is for ssize_t). > > While %zd works for ssize_t in glibc, POSIX doesn't guarantee that it'll work, > as ssize_t might not have the same width as size_t. (If memory serves this > goes back to the bad old days when size_t was 64 bits and ssize_t 32 bits on > some platforms.) So if we document %zd we should say it's a GNU extension to > POSIX, or something like that. %zd is for the signed type corresponding to size_t; that's in ISO C. The GNU extension would be a guarantee that ssize_t is the signed type corresponding to size_t (if we do guarantee that). -- Joseph S. Myers joseph@xxxxxxxxxxxxxxxx
