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 .

IEEE/The Open Group                                   2003                                              CTIME(P)