If your system provides threads, it will probably provide a

set of thread-safe variants of standard C library routines.

A small number of these are mandated by the POSIX standard,

and many Unix vendors provide their own useful supersets,

including functions such as gethostbyname_r().

Unfortunately, the supersets that different vendors support

do not necessarily overlap, so you can only safely use the

standard POSIX-mandated functions. The thread-safe routines

are conceptually "cleaner" than their stateful

counterparts, though, so it is good practice to use them

wherever and whenever you can.