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LOCALTIME(P)		   POSIX Programmer's Manual		  LOCALTIME(P)

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 require‐
       ments described here and the ISO C standard is unintentional. This vol‐
       ume 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	local‐
       time() 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	 Defi‐
       nitions 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 struc‐
       ture 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 struc‐
       ture 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), local‐
       time() 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 local‐
       time() 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 Defi‐
       nitions 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			  LOCALTIME(P)
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