NAME
       strftime - convert date and time to a string

SYNOPSIS
       #include <time.h>

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

DESCRIPTION
       The strftime() function shall place bytes into the array pointed to by
       s  as  controlled  by the string pointed to by format. The format is a
       character string, beginning and ending in its initial shift state,  if
       any.  The format string consists of zero or more conversion specifica-
       tions and ordinary characters.  A conversion specification consists of
       a ā%ā character, possibly followed by an E or O modifier, and a termi-
       nating conversion specifier character that determines  the  conversion
       specificationās  behavior. All ordinary characters (including the ter-
       minating null byte) are copied unchanged into the  array.  If  copying
       takes  place  between objects that overlap, the behavior is undefined.
       No more than maxsize bytes are placed into the array. Each  conversion
       specifier  is  replaced  by appropriate characters as described in the
       following list. The appropriate characters are  determined  using  the
       LC_TIME  category  of  the current locale and by the values of zero or
       more members of the broken-down time structure pointed to by  timeptr,
       as  specified  in brackets in the description. If any of the specified
       values are outside the normal range, the characters stored are unspec-
       ified.

       Local  timezone  information  is  used  as  though  strftime()  called
       tzset().

       The following conversion specifications are supported:

       %a     Replaced by the localeās abbreviated weekday name. [ tm_wday]

       %A     Replaced by the localeās full weekday name. [ tm_wday]

       %b     Replaced by the localeās abbreviated month name. [ tm_mon]

       %B     Replaced by the localeās full month name. [ tm_mon]

       %c     Replaced by the localeās appropriate date and time  representa-
              tion.      (See     the     Base    Definitions    volume    of
              IEEE Std 1003.1-2001, <time.h>.)

       %C     Replaced by the year divided by 100 and truncated to  an  inte-
              ger, as a decimal number [00,99]. [ tm_year]

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

       %D     Equivalent to %m / %d / %y . [ tm_mon, tm_mday, tm_year]

       %e     Replaced by the day of the month as a decimal number [1,31];  a
              single digit is preceded by a space. [ tm_mday]

       %F     Equivalent  to  %Y  -  %m - %d (the ISO 8601:2000 standard date
              format). [ tm_year, tm_mon, tm_mday]

       %g     Replaced by the last 2  digits  of  the  week-based  year  (see
              below)  as  a  decimal  number  [00,99].  [  tm_year,  tm_wday,
              tm_yday]

       %G     Replaced by the week-based year (see below) as a decimal number
              (for example, 1977). [ tm_year, tm_wday, tm_yday]

       %h     Equivalent to %b . [ tm_mon]

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

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

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

       %m     Replaced by the month as a decimal number [01,12]. [ tm_mon]

       %M     Replaced by the minute as a decimal number [00,59]. [ tm_min]

       %n     Replaced by a <newline>.

       %p     Replaced by the localeās equivalent of either a.m.  or  p.m.  [
              tm_hour]

       %r     Replaced by the time in a.m. and p.m. notation;    in the POSIX
              locale this shall be equivalent to  %I  :  %M  :  %S  %p  .   [
              tm_hour, tm_min, tm_sec]

       %R     Replaced  by  the  time  in  24-hour  notation  ( %H : %M ).  [
              tm_hour, tm_min]

       %S     Replaced by the second as a decimal number [00,60]. [ tm_sec]

       %t     Replaced by a <tab>.

       %T     Replaced by the time ( %H : %M  :  %S  ).  [  tm_hour,  tm_min,
              tm_sec]

       %u     Replaced  by the weekday as a decimal number [1,7], with 1 rep-
              resenting Monday. [ tm_wday]

       %U     Replaced by the week number of the year  as  a  decimal  number
              [00,53].   The first Sunday of January is the first day of week
              1; days in the new year before this are in week 0.  [  tm_year,
              tm_wday, tm_yday]

       %V     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  con-
              taining  1  January has four or more days in the new year, then
              it is considered week 1. Otherwise, it is the last week of  the
              previous  year,  and  the next week is week 1. Both January 4th
              and the first Thursday of January  are  always  in  week  1.  [
              tm_year, tm_wday, tm_yday]

       %w     Replaced  by the weekday as a decimal number [0,6], with 0 rep-
              resenting Sunday. [ tm_wday]

       %W     Replaced by the week number of the year  as  a  decimal  number
              [00,53].   The first Monday of January is the first day of week
              1; days in the new year before this are in week 0.  [  tm_year,
              tm_wday, tm_yday]

       %x     Replaced  by the localeās appropriate date representation. (See
              the Base Definitions volume of IEEE Std 1003.1-2001, <time.h>.)

       %X     Replaced  by the localeās appropriate time representation. (See
              the Base Definitions volume of IEEE Std 1003.1-2001, <time.h>.)

       %y     Replaced by the last two digits of the year as a decimal number
              [00,99].  [ tm_year]

       %Y     Replaced by the year as a decimal number (for example, 1997). [
              tm_year]

       %z     Replaced  by  the offset from UTC in the ISO 8601:2000 standard
              format ( +hhmm or -hhmm ), or by no characters if  no  timezone
              is  determinable. For example, "-0430" means 4 hours 30 minutes
              behind UTC (west of Greenwich).    If  tm_isdst  is  zero,  the
              standard time offset is used. If tm_isdst is greater than zero,
              the daylight savings time offset is used. If tm_isdst is  nega-
              tive, no characters are returned.  [ tm_isdst]

       %Z     Replaced  by  the timezone name or abbreviation, or by no bytes
              if no timezone information exists. [ tm_isdst]

       %%     Replaced by % .

       If a conversion specification does not correspond to any of the above,
       the behavior is undefined.

       If a struct tm broken-down time structure is created by localtime() or
       localtime_r(), or modified by mktime(), and the value of TZ is  subse-
       quently  modified,  the results of the %Z and %z strftime() conversion
       specifiers are undefined, when strftime() is called with such  a  bro-
       ken-down time structure.

       If  a  struct  tm broken-down time structure is created or modified by
       gmtime() or gmtime_r(), it is unspecified whether the result of the %Z
       and  %z  conversion specifiers shall refer to UTC or the current local
       timezone, when strftime() is  called  with  such  a  broken-down  time
       structure.

   Modified Conversion Specifiers
       Some  conversion  specifiers  can  be  modified by the E or O modifier
       characters to indicate that an  alternative  format  or  specification
       should  be  used  rather  than the one normally used by the unmodified
       conversion specifier. If the alternative format or specification  does
       not exist for the current locale (see ERA in the Base Definitions vol-
       ume of IEEE Std 1003.1-2001, Section  7.3.5,  LC_TIME),  the  behavior
       shall be as if the unmodified conversion specification were used.

       %Ec    Replaced  by the localeās alternative appropriate date and time
              representation.

       %EC    Replaced by the name of the base year (period) in the  localeās
              alternative representation.

       %Ex    Replaced by the localeās alternative date representation.

       %EX    Replaced by the localeās alternative time representation.

       %Ey    Replaced  by  the  offset  from %EC (year only) in the localeās
              alternative representation.

       %EY    Replaced by the full alternative year representation.

       %Od    Replaced by the day of the month, using the  localeās  alterna-
              tive  numeric  symbols,  filled as needed with leading zeros if
              there is any alternative symbol for zero; otherwise, with lead-
              ing spaces.

       %Oe    Replaced  by  the day of the month, using the localeās alterna-
              tive numeric symbols, filled as needed with leading spaces.

       %OH    Replaced by the hour (24-hour clock) using the localeās  alter-
              native numeric symbols.

       %OI    Replaced  by the hour (12-hour clock) using the localeās alter-
              native numeric symbols.

       %Om    Replaced by the month using the  localeās  alternative  numeric
              symbols.

       %OM    Replaced  by the minutes using the localeās alternative numeric
              symbols.

       %OS    Replaced by the seconds using the localeās alternative  numeric
              symbols.

       %Ou    Replaced by the weekday as a number in the localeās alternative
              representation (Monday=1).

       %OU    Replaced by the week number of the year (Sunday  as  the  first
              day of the week, rules corresponding to %U ) using the localeās
              alternative numeric symbols.

       %OV    Replaced by the week number of the year (Monday  as  the  first
              day of the week, rules corresponding to %V ) using the localeās
              alternative numeric symbols.

       %Ow    Replaced by the number of  the  weekday  (Sunday=0)  using  the
              localeās alternative numeric symbols.

       %OW    Replaced  by  the  week number of the year (Monday as the first
              day of the week) using the localeās  alternative  numeric  sym-
              bols.

       %Oy    Replaced  by  the  year  (offset  from  %C ) using the localeās
              alternative numeric symbols.

       %g , %G , and %V give values according to the  ISO 8601:2000  standard
       week-based year. In this system, weeks begin on a Monday and week 1 of
       the year is the week that includes January 4th, which is also the week
       that  includes  the  first Thursday of the year, and is also the first
       week that contains at least four days in the year. If the first Monday
       of January is the 2nd, 3rd, or 4th, the preceding days are part of the
       last week of the preceding year; thus, for Saturday 2nd January  1999,
       %G  is  replaced  by 1998 and %V is replaced by 53.  If December 29th,
       30th, or 31st is a Monday, it and any following days are part of  week
       1  of  the following year. Thus, for Tuesday 30th December 1997, %G is
       replaced by 1998 and %V is replaced by 01.

       If a conversion specifier is not one of the  above,  the  behavior  is
       undefined.

RETURN VALUE
       If  the total number of resulting bytes including the terminating null
       byte is not more than maxsize, strftime() shall return the  number  of
       bytes  placed into the array pointed to by s, not including the termi-
       nating null byte. Otherwise, 0 shall be returned and the  contents  of
       the array are unspecified.

ERRORS
       No errors are defined.

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 .

