ctime
=====

POSIX specification:
 https://pubs.opengroup.org/onlinepubs/9699919799/functions/ctime.html

Gnulib module: ctime

Portability problems fixed by Gnulib:

  * On native Windows platforms (mingw, MSVC), this function works incorrectly when the environment variable TZ has been set by Cygwin.

Portability problems not fixed by Gnulib:

  * This function may overflow its internal buffer if an invalid year is passed.

  * The ctime function need not be reentrant, and consequently is not required to be thread safe.  Implementations of ctime typically write the timestamp into static buffer.  If two threads call ctime at roughly the same time, you might end up with the wrong date in one of the threads, or some undefined string.  There is a re-entrant interface ctime_r.

  * Native Windows platforms (mingw, MSVC) support only a subset of time zones supported by GNU or specified by POSIX.  See tzset.

A more flexible function is strftime.  However, note that it is locale dependent.