STRFTIME(3)               OpenBSD Programmer's Manual              STRFTIME(3)

NAME
     strftime - format date and time



SYNOPSIS
     #include <time.h>

     size_t
     strftime(char *buf, size_t maxsize, const char *format,
             const struct tm *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 array.  If the
     total number of resulting characters, including the terminating NUL char-
     acter, is not more than maxsize, strftime() returns the number of charac-
     ters 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 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.

     %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].

     %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].

     %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.

     %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.

     %%    is replaced by `%'.

     %+    is replaced by the date and time in date(1) format.

SEE ALSO
     date(1),  printf(1),  ctime(3),  getenv(3),  printf(3),  strptime(3),
     time(3),  tzset(3),  tzfile(5)

STANDARDS
     The strftime() function conforms to ANSI X3.159-1989 (``ANSI C'').

     The `%G', `%g', `%k', and `%l' 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.

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

     Note that while this implementation of strftime() will always NUL termi-
     nate buf, other implementations may not do so when maxsiz is not large
     enough to store the entire time string.  The contents of buf are imple-
     mentation specific in this case.

OpenBSD 2.6                    January 18, 1998                              3