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 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 Defini-
       tions 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
",
		      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.
",
		  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 Technol-
       ogy -- 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)