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NAME
    HTTP::Date - date conversion routines

SYNOPSIS
     use HTTP::Date;

$string = time2str($time);    # Format as GMT ASCII time
     $time = str2time($string);    # convert ASCII date to machine time

DESCRIPTION
    This module provides functions that deal the date formats used by the
    HTTP protocol (and then some more). Only the first two functions,
    time2str() and str2time(), are exported by default.

time2str( [$time] )
        The time2str() function converts a machine time (seconds since
        epoch) to a string. If the function is called without an argument or
        with an undefined argument, it will use the current time.

The string returned is in the format preferred for the HTTP
        protocol. This is a fixed length subset of the format defined by RFC
        1123, represented in Universal Time (GMT). An example of a time
        stamp in this format is:

Sun, 06 Nov 1994 08:49:37 GMT

str2time( $str [, $zone] )
        The str2time() function converts a string to machine time. It
        returns `undef' if the format of $str is unrecognized, otherwise
        whatever the `Time::Local' functions can make out of the parsed
        time. Dates before the system's epoch may not work on all operating
        systems. The time formats recognized are the same as for
        parse_date().

The function also takes an optional second argument that specifies
        the default time zone to use when converting the date. This
        parameter is ignored if the zone is found in the date string itself.
        If this parameter is missing, and the date string format does not
        contain any zone specification, then the local time zone is assumed.

If the zone is not "`GMT'" or numerical (like "`-0800'" or
        "`+0100'"), then the `Time::Zone' module must be installed in order
        to get the date recognized.

parse_date( $str )
        This function will try to parse a date string, and then return it as
        a list of numerical values followed by a (possible undefined) time
        zone specifier; ($year, $month, $day, $hour, $min, $sec, $tz). The
        $year returned will not have the number 1900 subtracted from it and
        the $month numbers start with 1.

In scalar context the numbers are interpolated in a string of the
        "YYYY-MM-DD hh:mm:ss TZ"-format and returned.

If the date is unrecognized, then the empty list is returned.

The function is able to parse the following formats:

"Wed, 09 Feb 1994 22:23:32 GMT"       -- HTTP format
         "Thu Feb  3 17:03:55 GMT 1994"        -- ctime(3) format
         "Thu Feb  3 00:00:00 1994",           -- ANSI C asctime() format
         "Tuesday, 08-Feb-94 14:15:29 GMT"     -- old rfc850 HTTP format
         "Tuesday, 08-Feb-1994 14:15:29 GMT"   -- broken rfc850 HTTP format

"03/Feb/1994:17:03:55 -0700"   -- common logfile format
         "09 Feb 1994 22:23:32 GMT"     -- HTTP format (no weekday)
         "08-Feb-94 14:15:29 GMT"       -- rfc850 format (no weekday)
         "08-Feb-1994 14:15:29 GMT"     -- broken rfc850 format (no weekday)

"1994-02-03 14:15:29 -0100"    -- ISO 8601 format
         "1994-02-03 14:15:29"          -- zone is optional
         "1994-02-03"                   -- only date
         "1994-02-03T14:15:29"          -- Use T as separator
         "19940203T141529Z"             -- ISO 8601 compact format
         "19940203"                     -- only date

"08-Feb-94"         -- old rfc850 HTTP format    (no weekday, no time)
         "08-Feb-1994"       -- broken rfc850 HTTP format (no weekday, no time)
         "09 Feb 1994"       -- proposed new HTTP format  (no weekday, no time)
         "03/Feb/1994"       -- common logfile format     (no time, no offset)

"Feb  3  1994"      -- Unix 'ls -l' format
         "Feb  3 17:03"      -- Unix 'ls -l' format

"11-15-96  03:52PM" -- Windows 'dir' format

The parser ignores leading and trailing whitespace. It also allow
        the seconds to be missing and the month to be numerical in most
        formats.

If the year is missing, then we assume that the date is the first
        matching date *before* current month. If the year is given with only
        2 digits, then parse_date() will select the century that makes the
        year closest to the current date.

time2iso( [$time] )
        Same as time2str(), but returns a "YYYY-MM-DD hh:mm:ss"-formatted
        string representing time in the local time zone.

time2isoz( [$time] )
        Same as time2str(), but returns a "YYYY-MM-DD hh:mm:ssZ"-formatted
        string representing Universal Time.