NAME

       ctime, ctime_r - convert a time value to a date and time string

SYNOPSIS

       #include <time.h>

       char *ctime(const time_t *clock);

       char *ctime_r(const time_t *clock, char *buf);

DESCRIPTION

       For  ctime():    The  functionality  described  on this reference page is aligned with the
       ISO C standard. Any conflict  between  the  requirements  described  here  and  the  ISO C
       standard  is  unintentional.  This  volume  of  IEEE Std 1003.1-2001  defers  to the ISO C
       standard.

       The ctime() function shall convert the time pointed to  by  clock,  representing  time  in
       seconds since the Epoch, to local time in the form of a string. It shall be equivalent to:

              asctime(localtime(clock))

       The  asctime(), ctime(), gmtime(), and localtime() functions shall return values in one of
       two static objects: a broken-down time structure and an array of char. Execution of any of
       the  functions may overwrite the information returned in either of these objects by any of
       the other functions.

       The ctime() function need not be  reentrant.  A  function  that  is  not  required  to  be
       reentrant is not required to be thread-safe.

       The  ctime_r()  function shall convert the calendar time pointed to by clock to local time
       in exactly the same form as ctime() and put the string into the array pointed  to  by  buf
       (which shall be at least 26 bytes in size) and return buf.

       Unlike ctime(), the thread-safe version ctime_r() is not required to set tzname.

RETURN VALUE

       The  ctime() function shall return the pointer returned by asctime() with that broken-down
       time as an argument.

       Upon successful completion, ctime_r() shall return a pointer to the string pointed  to  by
       buf. When an error is encountered, a null pointer shall be returned.

ERRORS

       No errors are defined.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       Values  for  the  broken-down  time  structure  can  be  obtained  by  calling gmtime() or
       localtime().  The  ctime()   function   is   included   for   compatibility   with   older
       implementations,  and  does  not  support  localized  date and time formats.  Applications
       should use the strftime() function to achieve maximum portability.

       The ctime_r() function is thread-safe and shall return values in  a  user-supplied  buffer
       instead of possibly using a static data area that may be overwritten by each call.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       asctime()  ,  clock()  ,  difftime()  ,  gmtime()  , localtime() , mktime() , strftime() ,
       strptime() , time() , utime() ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <time.h>

COPYRIGHT

       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group  Standard  is  the  referee  document.  The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .