STRFTIME(3) | Library Functions Manual | STRFTIME(3) |
strftime
,
strftime_l
— format date and
time
#include
<time.h>
size_t
strftime
(char *buf,
size_t maxsize, const char
*format, const struct tm *timeptr);
size_t
strftime_l
(char *buf,
size_t maxsize, const char
*format, const struct tm *timeptr,
locale_t locale);
These functions format the information from timeptr (as described in mktime(3)) 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.
Each conversion specification is replaced by the characters as follows which are then copied into the buffer.
%A
%a
%B
%b
or %h
%C
%c
%D
%m/%d/%y
”.%d
%e
%F
%Y-%m-%d
”.%G
%g
%H
%I
%j
%k
%l
%M
%m
%n
%p
%R
%H:%M
”.%r
%S
%s
%T
%H:%M:%S
”.%t
%U
%u
%V
%v
%e-%b-%Y
”.%W
%w
%X
%x
%Y
%y
%Z
%z
+HHMM
” or
“-HHMM
” as appropriate, with
positive values representing locations east of Greenwich, or by the empty
string if this is not determinable.%%
%
’.%+
The OpenBSD implementation always uses the C locale and ignores the global locale, the thread-specific locale, and the locale argument.
If the total number of resulting characters, including the
terminating NUL character, is not more than maxsize,
strftime
() returns the number of characters placed
in the array, not counting the terminating NUL. Otherwise, zero is
returned.
On other operating systems, the behaviour of
strftime
() may depend on the
LC_TIME
locale(1).
date(1), printf(1), ctime(3), getenv(3), printf(3), strptime(3), time(3), tzset(3), tzfile(5)
The strftime
() function conforms to
ISO/IEC 9899:1999 (“ISO C99”),
and strftime_l
() to IEEE Std
1003.1-2008 (“POSIX.1”), except that the
‘E
’ and
‘O
’ conversion modifiers are ignored
by this implementation.
The ‘%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.
A predecessor to strftime
(),
ptime
(), first appeared in
Version 1 AT&T UNIX. The
strftime
() function has been available since
4.3BSD-Reno, and
strftime_l
() since OpenBSD
6.2.
Keith Bostic implemented the
BSD version of strftime
() in
1989.
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
maxsize is not large enough to store the entire time
string. The contents of buf are implementation
specific in this case.
September 5, 2017 | OpenBSD-6.4 |