According to POSIX.1-2004,
.BR localtime ()
is required to behave as though
-.BR tzset ()
+.BR tzset (3)
was called, while
.BR localtime_r ()
does not have this requirement.
.\" See http://thread.gmane.org/gmane.comp.time.tz/2034/
For portable code
-.BR tzset ()
+.BR tzset (3)
should be called before
.BR localtime_r ().
.SH "SEE ALSO"