strftime - format date and time
#include <time.h>
size_t
strftime(char *buf, size_t maxsize, const char *format,
const struct tm *timeptr);
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 array. If the
total number of resulting characters, including the terminating NUL character,
is not more than maxsize, strftime() returns the number of characters
in the array, not counting the terminating NUL. Otherwise, zero is
returned.
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
representation.
%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''.
%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 number
(00-99).
%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 (00-61).
The range
of seconds is (00-61) instead of (00-59) to allow for
the periodic
occurrence of leap seconds and double leap seconds.
%s is replaced by the number of seconds since the Epoch,
UTC (see
mktime(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). If the week
containing
January 1 has four or more days in the new year, then
it is week 1;
otherwise it is week 53 of the previous year, and the
next week is
week 1.
%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 name, or by the empty
string if this
is not determinable.
%z is replaced by the offset from UTC in the format
``+HHMM'' or
``-HHMM'' as appropriate, with positive values representing locations
east of Greenwich, or by the empty string if
this is not determinable.
%% is replaced by `%'.
%+ is replaced by the date and time in date(1) format.
date(1), printf(1), ctime(3), getenv(3), printf(3), strptime(3), time(3),
tzset(3), tzfile(5)
The strftime() function conforms to ANSI X3.159-1989 (``ANSI
C'').
The `%G', `%g', `%k', `%l', `%s', `%v', and `%+' conversion
specifications
are extensions.
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 Sunday
(day 7). For example, the first week of the year 1997
lasts from
1996-12-30 to 1997-01-05.
There is no conversion specification for the phase of the
moon.
Note that while this implementation of strftime() will always NUL terminate
buf, other implementations may not do so when maxsiz is
not large
enough to store the entire time string. The contents of buf
are implementation
specific in this case.
OpenBSD 3.6 January 18, 1998
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