NAME

       localtime, localtime_r - convert a time value to a broken-down local time

SYNOPSIS

       #include <time.h>

       struct tm *localtime(const time_t *timer);

       struct tm *localtime_r(const time_t *restrict timer,
              struct tm *restrict result);

DESCRIPTION

       For  localtime():   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 localtime() function shall convert the time in seconds since the Epoch pointed  to  by
       timer  into  a  broken-down time, expressed as a local time. The function corrects for the
       timezone and any seasonal time adjustments.     Local  timezone  information  is  used  as
       though localtime() calls tzset().

       The  relationship  between  a  time  in  seconds  since  the  Epoch used as an argument to
       localtime() and the tm structure (defined in the <time.h> header) is that the result shall
       be  as specified in the expression given in the definition of seconds since the Epoch (see
       the Base Definitions volume of  IEEE Std 1003.1-2001,  Section  4.14,  Seconds  Since  the
       Epoch)  corrected  for  timezone and any seasonal time adjustments, where the names in the
       structure and in the expression correspond.

       The same relationship shall apply for localtime_r().

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

       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 type char.  Execution  of
       any  of the functions may overwrite the information returned in either of these objects by
       any of the other functions.

       The localtime_r() function shall convert the time in seconds since the Epoch pointed to by
       timer  into  a  broken-down  time  stored  in  the  structure  to which result points. The
       localtime_r() function shall also return a pointer to that same structure.

       Unlike localtime(), the reentrant version is not required to set tzname.

RETURN VALUE

       Upon successful completion, the localtime() function shall return a pointer to the broken-
       down time structure. If an error is detected, localtime() shall return a null pointer  and
       set errno to indicate the error.

       Upon successful completion, localtime_r() shall return a pointer to the structure  pointed
       to by the argument result.

ERRORS

       The localtime() function shall fail if:

       EOVERFLOW
              The result cannot be represented.

       The following sections are informative.

EXAMPLES

   Getting the Local Date and Time
       The  following example uses the time() function to calculate the time elapsed, in seconds,
       since January 1, 1970 0:00 UTC (the Epoch), localtime() to convert that value to a broken-
       down time, and asctime() to convert the broken-down time values into a printable string.

              #include <stdio.h>
              #include <time.h>

              int main(void)
              {
                  time_t result;

                  result = time(NULL);
                  printf("%s%ju secs since the Epoch\n",
                      asctime(localtime(&result)),
                          (uintmax_t)result);
                  return(0);
              }

       This example writes the current time to stdout in a form like this:

              Wed Jun 26 10:32:15 1996
              835810335 secs since the Epoch

   Getting the Modification Time for a File
       The  following  example  gets  the  modification time for a file. The localtime() function
       converts the time_t value of the last modification date, obtained by a  previous  call  to
       stat(), into a tm structure that contains the year, month, day, and so on.

              #include <time.h>
              ...
              struct stat statbuf;
              ...
              tm = localtime(&statbuf.st_mtime);
              ...

   Timing an Event
       The following example gets the current time, converts it to a string using localtime() and
       asctime(), and prints it to standard output using fputs(). It then prints  the  number  of
       minutes to an event being timed.

              #include <time.h>
              #include <stdio.h>
              ...
              time_t now;
              int minutes_to_event;
              ...
              time(&now);
              printf("The time is ");
              fputs(asctime(localtime(&now)), stdout);
              printf("There are still %d minutes to the event.\n",
                  minutes_to_event);
              ...

APPLICATION USAGE

       The  localtime_r()  function  is  thread-safe and returns 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() , ctime() , difftime() , getdate() , gmtime() , 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 .