Standard C Library Functions                         strftime(3C)


NAME

     strftime, cftime, ascftime - convert date and time to string


SYNOPSIS

     #include <time.h>

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

     int cftime(char *s, char *format, const time_t *clock);

     int ascftime(char *s, const char *format,
          const struct tm *timeptr);


DESCRIPTION

     The strftime(), ascftime(),  and  cftime()  functions  place
     bytes  into  the  array pointed to by s as controlled by the
     string pointed to by format.  The format string consists  of
     zero  or more conversion specifications and ordinary charac-
     ters.  A conversion specification consists of  a  '%'  (per-
     cent)  character and one or two terminating conversion char-
     acters  that  determine   the   conversion   specification's
     behavior.   All ordinary characters (including the terminat-
     ing null byte) are copied unchanged into the  array  pointed
     to  by s.  If copying takes place between objects that over-
     lap, the behavior is undefined. For strftime(), no more than
     maxsize bytes are placed into the array.

     If format is (char *)0, then the locale's default format  is
     used.  For  strftime() the default format is the same as %c;
     for cftime() and ascftime() the default format is  the  same
     as  %C.   cftime() and ascftime() first try to use the value
     of the environment variable CFTIME, and if that is undefined
     or empty, the default format is used.

     Each conversion specification  is  replaced  by  appropriate
     characters as described in the following list. The appropri-
     ate characters are determined by the LC_TIME category of the
     program's  locale  and by the values contained in the struc-
     ture pointed to by timeptr for  strftime()  and  ascftime(),
     and by the time represented by clock for cftime().

     %%    Same as %.

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Standard C Library Functions                         strftime(3C)

     %a    Locale's abbreviated weekday name.

     %A    Locale's full weekday name.

     %b    Locale's abbreviated month name.

     %B    Locale's full month name.

  Default
     %c    Locale's appropriate date and time represented as:

             %a %b %d %H:%M:%S %Y

           This is the default  behavior  as  well  as  standard-
           conforming  behavior  for standards first supported by
           releases prior to Solaris 2.4. See standards(5).

  Standard conforming
     %c    Locale's appropriate date and time represented as:

             %a %b %e %H:%M:%S %Y

           This is  standard-conforming  behavior  for  standards
           first supported by Solaris 2.4 through Solaris 10.

  Default
     %C    Locale's date and time representation as  produced  by
           date(1).

           This is the default  behavior  as  well  as  standard-
           conforming  behavior  for standards first supported by
           releases prior to Solaris 2.4.

  Standard conforming
     %C    Century number (the year divided by 100 and  truncated
           to an integer as a decimal number [01,99]).

           This is  standard-conforming  behavior  for  standards
           first supported by Solaris 2.4 through Solaris 10.

     %d    Day of month [01,31].

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Standard C Library Functions                         strftime(3C)

     %D    Date as %m/%d/%y.

     %e    Day of month [1,31]; single  digits are preceded by  a
           space.

     %F    Equivalent to %Y-%m-%d  (the  ISO  8601:2000  standard
           date format).

     %g    Week-based year within century [00,99].

     %G    Week-based year, including the century [0000,9999].

     %h    Locale's abbreviated month name.

     %H    Hour (24-hour clock) [00,23].

     %I    Hour (12-hour clock) [01,12].

     %j    Day number of year [001,366].

     %k    Hour (24-hour clock) [0,23]; single  digits  are  pre-
           ceded by a space.

     %l    Hour (12-hour clock) [1,12]; single  digits  are  pre-
           ceded by a space.

     %m    Month number [01,12].

     %M    Minute [00,59].

     %n    Insert a NEWLINE.

     %p    Locale's equivalent of either a.m. or p.m.

     %r    Appropriate time representation in 12-hour clock  for-
           mat with %p.

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Standard C Library Functions                         strftime(3C)

     %R    Time as %H:%M.

     %S    Seconds [00,60]; the range of values is [00,60] rather
           than [00,59] to allow for the occasional leap second.

     %t    Insert a TAB.

     %T    Time as %H:%M:%S.

     %u    Weekday as a decimal number [1,7], with 1 representing
           Monday. See NOTES below.

     %U    Week number of year as a decimal number [00,53],  with
           Sunday as the first day of week 1.

     %V    The ISO 8601 week number as a decimal number  [01,53].
           In  the  ISO  8601 week-based system, weeks begin on a
           Monday and week  1  of  the  year  is  the  week  that
           includes  both  January  4th and the first Thursday of
           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.  See NOTES below.

     %w    Weekday as a decimal number [0,6], with 0 representing
           Sunday.

     %W    Week number of year as a decimal number [00,53],  with
           Monday as the first day of week 1.

     %x    Locale's appropriate date representation.

     %X    Locale's appropriate time representation.

     %y    Year within century [00,99].

     %Y    Year, including the century (for example 1993).

     %z    Replaced by offset from UTC in ISO 8601:2000  standard
           format  (+hhmm  or  -hhmm),  or by no characters if no

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Standard C Library Functions                         strftime(3C)

           time zone 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 if used. If tm_isdst is negative, no char-
           acters are returned.

     %Z    Time zone name or abbreviation, or no bytes if no time
           zone information exists.

     If a conversion specification does not correspond to any  of
     the  above  or  to any of the modified conversion specifica-
     tions listed below, the  behavior  is  undefined  and  0  is
     returned.

     The difference between %U and %W (and also between  modified
     conversion  specifications %OU and %OW) lies in which day is
     counted as the first of the week. Week number 1 is the first
     week  in  January  starting with a Sunday for %U or a Monday
     for %W.  Week number 0 contains those days before the  first
     Sunday or Monday in January for %U and %W, respectively.

  Modified Conversion Specifications
     Some conversion specifications can be modified by the E  and
     O modifiers to indicate that an alternate format or specifi-
     cation should be used rather than the one normally  used  by
     the  unmodified  conversion  specification. If the alternate
     format or  specification  does  not  exist  in  the  current
     locale, the behavior will be as if the unmodified specifica-
     tion were used.

     %Ec    Locale's  alternate   appropriate   date   and   time
            representation.

     %EC    Name of the base year (period) in the locale's alter-
            nate representation.

     %Eg    Offset  from  %EC  of  the  week-based  year  in  the
            locale's alternative representation.

     %EG    Full alternative  representation  of  the  week-based
            year.

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Standard C Library Functions                         strftime(3C)

     %Ex    Locale's alternate date representation.

     %EX    Locale's alternate time representation.

     %Ey    Offset from %EC (year only) in the locale's alternate
            representation.

     %EY    Full alternate year representation.

     %Od    Day of the month using the locale's alternate numeric
            symbols.

     %Oe    Same as %Od.

     %Og    Week-based year (offset  from  %C)  in  the  locale's
            alternate   representation  and  using  the  locale's
            alternate numeric symbols.

     %OH    Hour (24-hour clock)  using  the  locale's  alternate
            numeric symbols.

     %OI    Hour (12-hour clock)  using  the  locale's  alternate
            numeric symbols.

     %Om    Month using the locale's alternate numeric symbols.

     %OM    Minutes using the locale's alternate numeric symbols.

     %OS    Seconds using the locale's alternate numeric symbols.

     %Ou    Weekday as a number in the locale's alternate numeric
            symbols.

     %OU    Week number of the year (Sunday as the first  day  of
            the  week)  using the locale's alternate numeric sym-
            bols.

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Standard C Library Functions                         strftime(3C)

     %Ow    Number of the weekday (Sunday=0) using the   locale's
            alternate numeric symbols.

     %OW    Week number of the year (Monday as the first  day  of
            the  week)  using the locale's alternate numeric sym-
            bols.

     %Oy    Year (offset  from  %C)  in  the  locale's  alternate
            representation   and  using  the  locale's  alternate
            numeric symbols.

  Selecting the Output Language
     By default, the output of strftime(),  cftime(),  and  ascf-
     time() appear in U.S. English. The user can request that the
     output of  strftime(),  cftime(),  or  ascftime()  be  in  a
     specific language by setting the LC_TIME category using set-
     locale().

  Time Zone
     Local time zone information is used as though tzset(3C) were
     called.


RETURN VALUES

     The strftime(), cftime(), and  ascftime()  functions  return
     the number of characters placed into the array pointed to by
     s, not including the  terminating  null  character.  If  the
     total number of resulting characters including the terminat-
     ing null character is more than maxsize, strftime()  returns
     0 and the contents of the array are indeterminate.


EXAMPLES

     Example 1 An example of the strftime() function.

     The following example illustrates the use of strftime()  for
     the POSIX locale. It shows what the string in str would look
     like if the structure  pointed  to  by  tmptr  contains  the
     values   corresponding  to  Thursday,  August  28,  1986  at
     12:44:36.

       strftime (str, strsize, "%A %b %d %j", tmptr)

     This results in str containing "Thursday Aug 28 240".

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Standard C Library Functions                         strftime(3C)


ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | CSI                         | Enabled                     |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|
    | Standard                    | See below.                  |
    |_____________________________|_____________________________|

     For strftime(), see standards(5).


SEE ALSO

     date(1), ctime(3C), mktime(3C), setlocale(3C), strptime(3C),
     tzset(3C),    TIMEZONE(4),    zoneinfo(4),    attributes(5),
     environ(5), standards(5)


NOTES

     The conversion specification  for  %V  was  changed  in  the
     Solaris  7  release.  This  change  was  based on the public
     review draft of the ISO C9x standard at  that  time.  Previ-
     ously,  the specification stated that if the week containing
     1 January had fewer than four  days  in  the  new  year,  it
     became  week  53  of the previous year. The ISO C9x standard
     committee subsequently recognized  that  that  specification
     had been incorrect.

     The conversion specifications for %g, %G, %Eg, %EG, and  %Og
     were  added in the Solaris 7 release.  This change was based
     on the public review draft of the ISO C9x standard  at  that
     time.  These  specifications  are  evolving.  If the ISO C9x
     standard is finalized with  a  different  conclusion,  these
     specifications  will  change to conform to the ISO C9x stan-
     dard decision.

     The conversion specification  for  %u  was  changed  in  the
     Solaris 8 release. This change was based on the XPG4 specif-
     ication.

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Standard C Library Functions                         strftime(3C)

     If using the %Z specifier and zoneinfo timezones and if  the
     input  date is outside the range 20:45:52 UTC, December  13,
     1901 to 03:14:07 UTC, January 19, 2038,  the  timezone  name
     may not be correct.

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