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STRFTIME(3)	       FreeBSD Library Functions Manual		   STRFTIME(3)

NAME
     strftime, strftime_z -- format date and time

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <time.h>

     size_t
     strftime(char * restrict buf, size_t maxsize,
	 const char * restrict format, const struct tm * restrict timeptr);

     size_t
     strftime_z(const timezone_t tz, char * restrict buf, size_t maxsize,
	 const char * restrict format, const struct tm * restrict timeptr);

DESCRIPTION
     The strftime() function formats the information from timeptr into the
     buffer buf	according to the string	pointed	to by format.

     The format	string consists	of zero	or more	conversion specifications and
     ordinary characters.  All ordinary	characters are copied directly into
     the buffer.  A conversion specification consists of a percent sign	`%'
     and one other character.

     No	more than maxsize characters will be placed into the buffer.  If the
     total number of resulting characters, including the terminating null
     character,	is not more than maxsize, strftime() returns the number	of
     characters	in the buffer, not counting the	terminating null.  Otherwise,
     zero is returned and the contents of the buffer are undefined.

     Each conversion specification is replaced by the characters as follows
     which are then copied into	the buffer.

     %A	   is replaced by the locale's full weekday name.

     %a	   is replaced by the locale's abbreviated weekday name.

     %B	   is replaced by the locale's full month name.

     %b	or %h
	   is replaced by the locale's abbreviated month name.

     %C	   is replaced by the century (a year divided by 100 and truncated to
	   an integer) as a decimal number [00,99].

     %c	   is replaced by the locale's appropriate date	and time representa-
	   tion.

     %D	   is replaced by the date in the format "%m/%d/%y".

     %d	   is replaced by the day of the month as a decimal number [01,31].

     %e	   is replaced by the day of month as a	decimal	number [1,31]; single
	   digits are preceded by a blank.

     %F	   is replaced by the date in the format "%Y-%m-%d" (the ISO 8601 date
	   format).

     %G	   is replaced by the ISO 8601 year with century as a decimal number.

     %g	   is replaced by the ISO 8601 year without century as a decimal num-
	   ber (00-99).	 This is the year that includes	the greater part of
	   the week.  (Monday as the first day of a week).  See	also the `%V'
	   conversion specification.

     %H	   is replaced by the hour (24-hour clock) as a	decimal	number
	   [00,23].

     %I	   is replaced by the hour (12-hour clock) as a	decimal	number
	   [01,12].

     %j	   is replaced by the day of the year as a decimal number [001,366].

     %k	   is replaced by the hour (24-hour clock) as a	decimal	number [0,23];
	   single digits are preceded by a blank.

     %l	   is replaced by the hour (12-hour clock) as a	decimal	number [1,12];
	   single digits are preceded by a blank.

     %M	   is replaced by the minute as	a decimal number [00,59].

     %m	   is replaced by the month as a decimal number	[01,12].

     %n	   is replaced by a newline.

     %p	   is replaced by the locale's equivalent of either "AM" or "PM".

     %R	   is replaced by the time in the format "%H:%M".

     %r	   is replaced by the locale's representation of 12-hour clock time
	   using AM/PM notation.

     %S	   is replaced by the second as	a decimal number [00,60].  The range
	   of seconds is (00-60) instead of (00-59) to allow for the periodic
	   occurrence of leap seconds.

     %s	   is replaced by the number of	seconds	since the Epoch	(see
	   ctime(3)).

     %T	   is replaced by the time in the format "%H:%M:%S".

     %t	   is replaced by a tab.

     %U	   is replaced by the week number of the year (Sunday as the first day
	   of the week)	as a decimal number [00,53].

     %u	   is replaced by the weekday (Monday as the first day of the week) as
	   a decimal number [1,7].

     %V	   is replaced by the week number of the year (Monday as the first day
	   of the week)	as a decimal number [01,53]. According to ISO 8601 the
	   week	containing January 1 is	week 1 if it has four or more days in
	   the new year, otherwise it is week 53 of the	previous year, and the
	   next	week is	week 1.	 The year is given by the `%G' conversion
	   specification.

     %v	   is replaced by the date in the format "%e-%b-%Y".

     %W	   is replaced by the week number of the year (Monday as the first day
	   of the week)	as a decimal number [00,53].

     %w	   is replaced by the weekday (Sunday as the first day of the week) as
	   a decimal number [0,6].

     %X	   is replaced by the locale's appropriate time	representation.

     %x	   is replaced by the locale's appropriate date	representation.

     %Y	   is replaced by the year with	century	as a decimal number.

     %y	   is replaced by the year without century as a	decimal	number
	   [00,99].

     %Z	   is replaced by the time zone	abbreviation, or the empty string if
	   this	is not determinable.

     %z	   is replaced by the offset from the Prime Meridian in	the format
	   +HHMM or -HHMM (ISO 8601) as	appropriate, with positive values rep-
	   resenting locations east of Greenwich, or by	the empty string if
	   this	is not determinable.  The numeric time zone abbreviation -0000
	   is used when	the time is Universal Time but local time is indeter-
	   minate; by convention this is used for locations while uninhabited,
	   and corresponds to a	zero offset when the time zone abbreviation
	   begins with "[-]".

     %+	   is replaced by national representation of the date and time (the
	   format is similar to	that produced by date(1)).  On NetBSD cur-
	   rently this only works for the C locale.

     %-*   GNU libc extension.	Do not do any padding when performing numeri-
	   cal outputs.

     %_*   GNU libc extension.	Explicitly specify space for padding.

     %0*   GNU libc extension.	Explicitly specify zero	for padding.

     %%	   is replaced by `%'.

     The strftime_z() function is similar to strftime(), but it	also takes a
     const timezone_t tz argument.

SEE ALSO
     date(1), printf(1), ctime(3), printf(3), strptime(3), tm(3)

STANDARDS
     The strftime() function conforms to ISO/IEC 9899:1999 ("ISO C99").	 The
     `%C', `%D', `%e', `%g', `%G', `%h', `%k', `%l', `%n', `%r', `%R', `%s',
     `%t', `%T', `%u', `%V', and `%v' conversion specifications	are exten-
     sions.

     Use of the	ISO 8601 conversions may produce non-intuitive results.	 Week
     01	of a year is per definition the	first week which has the Thursday in
     this year,	which is equivalent to the week	which contains the fourth day
     of	January.  In other words, the first week of a new year is the week
     which has the majority of its days	in the new year.  Week 01 might	also
     contain days from the previous year and the week before week 01 of	a year
     is	the last week (52 or 53) of the	previous year even if it contains days
     from the new year.	 A week	starts with Monday (day	1) and ends with Sun-
     day (day 7).  For example,	the first week of the year 1997	lasts from
     1996-12-30	to 1997-01-05.

BUGS
     There is no conversion specification for the phase	of the moon.

     A return value of zero does not necessarily indicate an error.  If	the
     resulting string is an empty string, the result value is zero and it is
     not possible to distinguish between success and error.  For example, in
     many locales %p yields an empty string.  This problem can be avoided by
     inserting an extra	space at the beginning of the format string and	then
     skipping over it or removing it from the result.

FreeBSD	13.0			 April 5, 2019			  FreeBSD 13.0

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | SEE ALSO | STANDARDS | BUGS

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