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Date::Manip::DM5(3pm) User Contributed Perl DocumentationDate::Manip::DM5(3pm)

       Date::Manip::DM5 - Date manipulation routines

        use Date::Manip;

        $version = DateManipVersion;

        @list = Date_Init();
        @list = Date_Init("VAR=VAL","VAR=VAL",...);

        $date = ParseDate(\@args);
        $date = ParseDate($string);
        $date = ParseDate(\$string);

        @date = UnixDate($date,@format);
        $date = UnixDate($date,@format);

        $delta = ParseDateDelta(\@args);
        $delta = ParseDateDelta($string);
        $delta = ParseDateDelta(\$string);

        @str = Delta_Format($delta,$dec,@format);
        $str = Delta_Format($delta,$dec,@format);

        $recur = ParseRecur($string,$base,$date0,$date1,$flags);
        @dates = ParseRecur($string,$base,$date0,$date1,$flags);

        $flag = Date_Cmp($date1,$date2);

        $d = DateCalc($d1,$d2 [,$errref] [,$del]);

        $date = Date_SetTime($date,$hr,$min,$sec);
        $date = Date_SetTime($date,$time);

        $date = Date_SetDateField($date,$field,$val [,$nocheck]);

        $date = Date_GetPrev($date,$dow,$today,$hr,$min,$sec);
        $date = Date_GetPrev($date,$dow,$today,$time);

        $date = Date_GetNext($date,$dow,$today,$hr,$min,$sec);
        $date = Date_GetNext($date,$dow,$today,$time);

        $name = Date_IsHoliday($date);

        $listref = Events_List($date);
        $listref = Events_List($date0,$date1);

        $date = Date_ConvTZ($date);
        $date = Date_ConvTZ($date,$from);
        $date = Date_ConvTZ($date,"",$to);
        $date = Date_ConvTZ($date,$from,$to);

        $flag = Date_IsWorkDay($date [,$flag]);

        $date = Date_NextWorkDay($date,$off [,$flag]);

        $date = Date_PrevWorkDay($date,$off [,$flag]);

        $date = Date_NearestWorkDay($date [,$tomorrowfirst]);

       The above routines all check to make sure that Date_Init is called.  If
       it hasn't been, they will call it automatically.  As a result, there is
       usually no need to call Date_Init explicitly unless you want to change
       some of the config variables (described below).  They also do error
       checking on the input.

       The routines listed below are intended primarily for internal use by
       other Date::Manip routines.  They do little or no error checking, and
       do not explicitly call Date_Init.  Those functions are all done in the
       main Date::Manip routines above.

       Because they are significantly faster than the full Date::Manip
       routines, they are available for use with a few caveats.  Since little
       or no error checking is done, it is the responsibility of the
       programmer to ensure that valid data (AND valid dates) are passed to
       them.  Passing invalid data (such as a non-numeric month) or invalid
       dates (Feb 31) will fail in unpredictable ways (possibly returning
       erroneous results).  Also, since Date_Init is not called by these, it
       must be called explicitly by the programmer before using these

       In the following routines, $y may be entered as either a 2 or 4 digit
       year (it will be converted to a 4 digit year based on the variable
       YYtoYYYY described below).  Month and day should be numeric in all
       cases.  Most (if not all) of the information below can be gotten from
       UnixDate which is really the way I intended it to be gotten, but there
       are reasons to use these (these are significantly faster).

        $day = Date_DayOfWeek($m,$d,$y);
        $secs = Date_SecsSince1970($m,$d,$y,$h,$mn,$s);
        $secs = Date_SecsSince1970GMT($m,$d,$y,$h,$mn,$s);
        $days = Date_DaysSince1BC($m,$d,$y);
        $day = Date_DayOfYear($m,$d,$y);
        ($y,$m,$d,$h,$mn,$s) = Date_NthDayOfYear($y,$n);
        $days = Date_DaysInYear($y);
        $days = Date_DaysInMonth($m,$y);
        $wkno = Date_WeekOfYear($m,$d,$y,$first);
        $flag = Date_LeapYear($y);
        $day = Date_DaySuffix($d);
        $tz = Date_TimeZone();

            @list = Date_Init();
            @list = Date_Init("VAR=VAL","VAR=VAL",...);

           Normally, it is not necessary to explicitly call Date_Init.  The
           first time any of the other routines are called, Date_Init will be
           called to set everything up.  If for some reason you want to change
           the configuration of Date::Manip, you can pass the appropriate
           string or strings into Date_Init to reinitialize things.

           The strings to pass in are of the form "VAR=VAL".  Any number may
           be included and they can come in any order.  VAR may be any
           configuration variable.  A list of all configuration variables is
           given in the section CUSTOMIZING DATE::MANIP below.  VAL is any
           allowed value for that variable.  For example, to switch from
           English to French and use non-US format (so that 12/10 is Oct 12),
           do the following:


           If Date_Init is called in list context, it will return a list of
           all config variables and their values suitable for passing in to
           Date_Init to return Date::Manip to the current state.  The only
           possible problem is that by default, holidays will not be erased,
           so you may need to prepend the "EraseHolidays=1" element to the

            $date = ParseDate(\@args);
            $date = ParseDate($string);
            $date = ParseDate(\$string);

           This takes an array or a string containing a date and parses it.
           When the date is included as an array (for example, the arguments
           to a program) the array should contain a valid date in the first
           one or more elements (elements after a valid date are ignored).
           Elements containing a valid date are shifted from the array.  The
           largest possible number of elements which can be correctly
           interpreted as a valid date are always used.  If a string is
           entered rather than an array, that string is tested for a valid
           date.  The string is unmodified, even if passed in by reference.

           The real work is done in the ParseDateString routine.

           The ParseDate routine is primarily used to handle command line
           arguments.  If you have a command where you want to enter a date as
           a command line argument, you can use Date::Manip to make something
           like the following work:

             mycommand -date Dec 10 1997 -arg -arg2

           No more reading man pages to find out what date format is required
           in a man page.

           Historical note: this is originally why the Date::Manip routines
           were written (though long before they were released as the
           Date::Manip module).  I was using a bunch of programs (primarily
           batch queue managers) where dates and times were entered as command
           line options and I was getting highly annoyed at the many different
           (but not compatible) ways that they had to be entered.  Date::Manip
           originally consisted of basically 1 routine which I could pass
           "@ARGV" to and have it remove a date from the beginning.

            $date = ParseDateString($string);

           This routine is called by ParseDate, but it may also be called
           directly to save some time (a negligible amount).

           NOTE:  One of the most frequently asked questions that I have
           gotten is how to parse seconds since the epoch.  ParseDateString
           cannot simply parse a number as the seconds since the epoch (it
           conflicts with some ISO-8601 date formats).  There are two ways to
           get this information.  First, you can do the following:

               $secs = ...         # seconds since Jan 1, 1970  00:00:00 GMT
               $date = DateCalc("Jan 1, 1970  00:00:00 GMT","+ $secs");

           Second, you can call it directly as:

               $date = ParseDateString("epoch $secs");

           To go backwards, just use the "%s" format of UnixDate:

               $secs = UnixDate($date,"%s");

           A full date actually includes 2 parts: date and time.  A time must
           include hours and minutes and can optionally include seconds,
           fractional seconds, an am/pm type string, and a time zone.  For

                [at] HH:MN              [Zone]
                [at] HH:MN         [am] [Zone]
                [at] HH:MN:SS      [am] [Zone]
                [at] HH:MN:SS.SSSS [am] [Zone]
                [at] HH            am   [Zone]

           Hours can be written using 1 or 2 digits, but the single digit form
           may only be used when no ambiguity is introduced (i.e. when it is
           not immediately preceded by a digit).

           A time is usually entered in 24 hour mode, but 12 hour mode can be
           used as well if AM/PM are entered (AM can be entered as AM or A.M.
           or other variations depending on the language).

           Fractional seconds are also supported in parsing but the fractional
           part is discarded (with NO rounding occurring).

           Time zones always appear immediately after the time.  A number of
           different forms are supported (see the section TIME ZONES below).

           Incidentally, the time is removed from the date before the date is
           parsed, so the time may appear before or after the date, or between
           any two parts of the date.

           Valid date formats include the ISO 8601 formats:

              YYYYwWWD      ex.  1965-W02-2
              YYYYDOY       ex.  1965-045

           In the above list, YYYY and YY signify 4 or 2 digit years, MM, DD,
           HH, MN, SS refer to two digit month, day, hour, minute, and second
           respectively.  F...  refers to fractional seconds (any number of
           digits) which will be ignored.  In all cases, the date and time
           parts may be separated by the letter "T" (but this is optional), so
              2002-12-10T12:00:00 are identical.

           The last 4 formats can be explained by example:  1965-w02-2 refers
           to Tuesday (day 2) of the 2nd week of 1965.  1965-045 refers to the
           45th day of 1965.

           In all cases, parts of the date may be separated by dashes "-".  If
           this is done, 1 or 2 digit forms of MM, DD, etc. may be used.  All
           dashes are optional except for those given in the table above
           (which MUST be included for that format to be correctly parsed).
           So 19980820, 1998-0820, 1998-08-20, 1998-8-20, and 199808-20 are
           all equivalent, but that date may NOT be written as 980820 (it must
           be written as 98-0820).

           NOTE:  Even though not allowed in the standard, the time zone for
           an ISO-8601 date is flexible and may be any of the time zones
           understood by Date::Manip.

           Additional date formats are available which may or may not be
           common including:

             MM/DD  **
             MM/DD/YY  **
             MM/DD/YYYY  **

             mmmDD       DDmmm                   mmmYYYY/DD     mmmYYYY
             mmmDD/YY    DDmmmYY     DD/YYmmm    YYYYmmmDD      YYYYmmm
             mmmDDYYYY   DDmmmYYYY   DDYYYYmmm   YYYY/DDmmm

           Where mmm refers to the name of a month.  All parts of the date can
           be separated by valid separators (space, "/", or ".").  The
           separator "-" may be used as long as it doesn't conflict with an
           ISO 8601 format, but this is discouraged since it is easy to
           overlook conflicts.  For example, the format MM/DD/YY is just fine,
           but MM-DD-YY does not work since it conflicts with YY-MM-DD.  To be
           safe, if "-" is used as a separator in a non-ISO format, they
           should be turned into "/" before calling the Date::Manip routines.
           As with ISO 8601 formats, all separators are optional except for
           those given as a "/" in the list above.

           ** Note that with these formats, Americans tend to write month
           first, but many other countries tend to write day first.  The
           latter behavior can be obtained by setting the config variable
           DateFormat to something other than "US" (see CUSTOMIZING
           DATE::MANIP below).

           Date separators are treated very flexibly (they are converted to
           spaces), so the following dates are all equivalent:

              12-10 / 1965
              12 // 10 -. 1965

           In some cases, this may actually be TOO flexible, but no attempt is
           made to trap this.

           Years can be entered as 2 or 4 digits, days and months as 1 or 2
           digits.  Both days and months must include 2 digits whenever they
           are immediately adjacent to another numeric part of the date or
           time.  Date separators are required if single digit forms of DD or
           MM are used.  If separators are not used, the date will either be
           unparsable or will get parsed incorrectly.

           Miscellaneous other allowed formats are:
             which dofw in mmm in YY      "first Sunday in June
                                          1996 at 14:00" **
             dofw week num YY             "Sunday week 22 1995" **
             which dofw YY                "22nd Sunday at noon" **
             dofw which week YY           "Sunday 22nd week in
                                          1996" **
             next/last dofw               "next Friday at noon"
             next/last week/month         "next month"
             in num days/weeks/months     "in 3 weeks at 12:00"
             num days/weeks/months later  "3 weeks later"
             num days/weeks/months ago    "3 weeks ago"
             dofw in num week             "Friday in 2 weeks"
             in num weeks dofw            "in 2 weeks on Friday"
             dofw num week ago            "Friday 2 weeks ago"
             num week ago dofw            "2 weeks ago Friday"
             last day in mmm in YY        "last day of October"
             dofw                         "Friday" (Friday of
                                          current week)
             Nth                          "12th", "1st" (day of
                                          current month)
             epoch SECS                   seconds since the epoch
                                          (negative values are

           ** Note that the formats "Sunday week 22" and "22nd Sunday" give
           very different behaviors.  "Sunday week 22" returns the Sunday of
           the 22nd week of the year based on how week 1 is defined.  ISO 8601
           defines week one to contain Jan 4, so "Sunday week 1" might be the
           first or second Sunday of the current year, or the last Sunday of
           the previous year.  "22nd Sunday" gives the actual 22nd time Sunday
           occurs in a given year, regardless of the definition of a week.

           Note that certain words such as "in", "at", "of", etc. which
           commonly appear in a date or time are ignored.  Also, the year is
           always optional.

           In addition, the following strings are recognized:
             today     (exactly now OR today at a given time if a time is
             now       (synonym for today)
             yesterday (exactly 24 hours ago unless a time is specified)
             tomorrow  (exactly 24 hours from now unless a time is specified)
             noon      (12:00:00)
             midnight  (00:00:00) Other languages have similar (and in some
           cases additional) strings.

           Some things to note:

           All strings are case insensitive.  "December" and "DEceMBer" both

           When a part of the date is not given, defaults are used: year
           defaults to current year; hours, minutes, seconds to 00.

           The year may be entered as 2 or 4 digits.  If entered as 2 digits,
           it will be converted to a 4 digit year.  There are several ways to
           do this based on the value of the YYtoYYYY variable (described
           below).  The default behavior it to force the 2 digit year to be in
           the 100 year period CurrYear-89 to CurrYear+10.  So in 1996, the
           range is [1907 to 2006], and the 2 digit year 05 would refer to
           2005 but 07 would refer to 1907.  See CUSTOMIZING DATE::MANIP below
           for information on YYtoYYYY for other methods.

           Dates are always checked to make sure they are valid.

           In all of the formats, the day of week ("Friday") can be entered
           anywhere in the date and it will be checked for accuracy.  In other
             "Tue Jul 16 1996 13:17:00" will work but
             "Jul 16 1996 Wednesday 13:17:00" will not (because Jul 16, 1996
           is Tuesday, not Wednesday).  Note that depending on where the
           weekday comes, it may give unexpected results when used in array
           context (with ParseDate).  For example, the date
           ("Jun","25","Sun","1990") would return June 25 of the current year
           since Jun 25, 1990 is not Sunday.

           The times "12:00 am", "12:00 pm", and "midnight" are not well
           defined.  For good or bad, I use the following convention in
             midnight = 12:00am = 00:00:00
             noon     = 12:00pm = 12:00:00 and the day goes from 00:00:00 to
           23:59:59.  In other words, midnight is the beginning of a day
           rather than the end of one.  The time 24:00:00 is also allowed
           (though it is automatically transformed to 00:00:00 of the
           following day).

           The format of the date returned is YYYYMMDDHH:MM:SS.  The advantage
           of this time format is that two times can be compared using simple
           string comparisons to find out which is later.  Also, it is readily
           understood by a human.  Alternate forms can be used if that is more
           convenient.  See Date_Init below and the config variable Internal.

           NOTE: The format for the date is going to change at some point in
           the future to YYYYMMDDHH:MN:SS+HHMN*FLAGS.  In order to maintain
           compatibility, you should use UnixDate to extract information from
           a date, and Date_Cmp to compare two dates.  The simple string
           comparison will only work for dates in the same time zone.

            @date = UnixDate($date,@format);
            $date = UnixDate($date,@format);

           This takes a date and a list of strings containing formats roughly
           identical to the format strings used by the UNIX date(1) command.
           Each format is parsed and an array of strings corresponding to each
           format is returned.

           $date may be any string that can be parsed by ParseDateString.

           The format options are:

                %y     year                     - 00 to 99
                %Y     year                     - 0001 to 9999
            Month, Week
                %m     month of year            - 01 to 12
                %f     month of year            - " 1" to "12"
                %b,%h  month abbreviation       - Jan to Dec
                %B     month name               - January to December
                %j     day of the year          - 001 to 366
                %d     day of month             - 01 to 31

                %e     day of month             - " 1" to "31"
                %v     weekday abbreviation     - " S"," M"," T"," W","Th"," F","Sa"
                %a     weekday abbreviation     - Sun to Sat
                %A     weekday name             - Sunday to Saturday
                %w     day of week              - 1 (Monday) to 7 (Sunday)
                %E     day of month with suffix - 1st, 2nd, 3rd...
                %H     hour                     - 00 to 23
                %k     hour                     - " 0" to "23"
                %i     hour                     - " 1" to "12"
                %I     hour                     - 01 to 12
                %p     AM or PM
            Minute, Second, Time zone
                %M     minute                   - 00 to 59
                %S     second                   - 00 to 59
                %Z     time zone                - "EDT"
                %z     time zone as GMT offset  - "+0100"
            Epoch (see NOTE 3 below)
                %s     seconds from 1/1/1970 GMT- negative if before 1/1/1970
                %o     seconds from Jan 1, 1970
                       in the current time zone
            Date, Time
                %c     %a %b %e %H:%M:%S %Y     - Fri Apr 28 17:23:15 1995
                %C,%u  %a %b %e %H:%M:%S %z %Y  - Fri Apr 28 17:25:57 EDT 1995
                %g     %a, %d %b %Y %H:%M:%S %z - Fri, 28 Apr 1995 17:23:15 EDT
                %D     %m/%d/%y                 - 04/28/95
                %x     %m/%d/%y or %d/%m/%y     - 04/28/95 or 28/04/28
                                                  (Depends on DateFormat variable)
                %l     date in ls(1) format (see NOTE 1 below)
                         %b %e $H:$M            - Apr 28 17:23  (if within 6 months)
                         %b %e  %Y              - Apr 28  1993  (otherwise)
                %r     %I:%M:%S %p              - 05:39:55 PM
                %R     %H:%M                    - 17:40
                %T,%X  %H:%M:%S                 - 17:40:58
                %V     %m%d%H%M%y               - 0428174095
                %Q     %Y%m%d                   - 19961025
                %q     %Y%m%d%H%M%S             - 19961025174058
                %P     %Y%m%d%H%M%S             - 1996102517:40:58
                %O     %Y-%m-%dT%H:%M:%S        - 1996-10-25T17:40:58
                %F     %A, %B %e, %Y            - Sunday, January  1, 1996
                %K     %Y-%j                    - 1997-045
            Special Year/Week formats (see NOTE 2 below)
                %G     year, Monday as first
                       day of week              - 0001 to 9999
                %W     week of year, Monday
                       as first day of week     - 01 to 53
                %L     year, Sunday as first
                       day of week              - 0001 to 9999
                %U     week of year, Sunday
                       as first day of week     - 01 to 53
                %J     %G-W%W-%w                - 1997-W02-2
            Other formats
                %n     insert a newline character
                %t     insert a tab character
                %%     insert a `%' character
                %+     insert a `+' character
            The following formats are currently unused but may be used in the future:
                N 1234567890 !@#$^&*()_|-=\`[];',./~{}:<>?
            They currently insert the character following the %, but may (and probably
            will) change in the future as new formats are added.

           If a lone percent is the final character in a format, it is

           The formats used in this routine were originally based on
           (version 3.2) by Terry McGonigal, as well as a couple taken from
           different versions of the Solaris date(1) command.  Also, several
           have been added which are unique to Date::Manip.

           NOTE 1:

           The ls format (%l) applies to date within the past OR future 6

           NOTE 2:

           The %U, %W, %L, %G, and %J formats are used to support the ISO-8601
           format: YYYY-wWW-D.  In this format, a date is written as a year,
           the week of the year, and the day of the week.  Technically, the
           week may be considered to start on any day of the week, but Sunday
           and Monday are the both common choices, so both are supported.

           The %W and %G formats return the week-of-year and the year treating
           weeks as starting on Monday.

           The %U and %L formats return the week-of-year and the year treating
           weeks as starting on Sunday.

           Most of the time, the %L and %G formats returns the same value as
           the %Y format, but there is a problem with days occurring in the
           first or last week of the year.

           The ISO-8601 representation of Jan 1, 1993 written in the YYYY-wWW-
           D format is actually 1992-W53-5.  In other words, Jan 1 is treated
           as being in the last week of the preceding year.  Depending on the
           year, days in the first week of a year may belong to the previous
           year, and days in the final week of a year may belong to the next
           year.  The week is assigned to the year which has most of the days.
           For example, if the week starts on Sunday, then the last week of
           2003 is 2003-12-28 to 2004-01-03.  This week is assigned to 2003
           since 4 of the days in it are in 2003 and only 3 of them are in
           2004.  The first week of 2004 starts on 2004-01-04.

           The %U and %W formats return a week-of-year number from 01 to 53.
           %L and %G return the corresponding year, and to get this type of
           information, you should always use the (%W,%G) combination or
           (%U,%L) combination. %Y should not be used as it will yield
           incorrect results.

           %J returns the full ISO-8601 format (%G-W%W-%w).

           NOTE 3:

           The %s and %o formats return negative values if the date is before
           the start of the epoch.  Other Unix utilities would return an
           error, or a zero, so if you are going to use Date::Manip in
           conjunction with these, be sure to check for a negative value.

            $delta = ParseDateDelta(\@args);
            $delta = ParseDateDelta($string);
            $delta = ParseDateDelta(\$string);

           This takes an array and shifts a valid delta date (an amount of
           time) from the array.  Recognized deltas are of the form:
             +Yy +Mm +Ww +Dd +Hh +MNmn +Ss
                    +4 hours +3mn -2second
                    + 4 hr 3 minutes -2
                    4 hour + 3 min -2 s
             mixed format
                    4 hour 3:-2

           A field in the format +Yy is a sign, a number, and a string
           specifying the type of field.  The sign is "+", "-", or absent
           (defaults to the next larger element).  The valid strings
           specifying the field type are:
              y:  y, yr, year, years
              m:  m, mon, month, months
              w:  w, wk, ws, wks, week, weeks
              d:  d, day, days
              h:  h, hr, hour, hours
              mn: mn, min, minute, minutes
              s:  s, sec, second, seconds

           Also, the "s" string may be omitted.  The sign, number, and string
           may all be separated from each other by any number of whitespace.

           In the date, all fields must be given in the order: Y M W D H MN S.
           Any number of them may be omitted provided the rest remain in the
           correct order.  In the 2nd (colon) format, from 2 to 7 of the
           fields may be given.  For example +D:+H:+MN:+S may be given to
           specify only four of the fields.  In any case, both the MN and S
           field may be present.  No spaces may be present in the colon

           Deltas may also be given as a combination of the two formats.  For
           example, the following is valid: +Yy +D:+H:+MN:+S.  Again, all
           fields must be given in the correct order.

           The word "in" may be given (prepended in English) to the delta ("in
           5 years") and the word "ago" may be given (appended in English) ("6
           months ago").  The "in" is completely ignored.  The "ago" has the
           affect of reversing all signs that appear in front of the
           components of the delta.  I.e. "-12 yr 6 mon ago" is identical to
           "+12yr +6mon" (don't forget that there is an implied minus sign in
           front of the 6 because when no sign is explicitly given, it carries
           the previously entered sign).

           One thing is worth noting.  The year/month and day/hour/min/sec
           parts are returned in a "normalized" form.  That is, the signs are
           adjusted so as to be all positive or all negative.  For example, "+
           2 day - 2hour" does not return "0:0:0:2:-2:0:0".  It returns
           "+0:0:0:1:22:0:0" (1 day 22 hours which is equivalent).  I find
           (and I think most others agree) that this is a more useful form.

           Since the year/month and day/hour/min/sec parts must be normalized
           separately there is the possibility that the sign of the two parts
           will be different.  So, the delta "+ 2years -10 months - 2 days + 2
           hours" produces the delta "+1:2:-0:1:22:0:0".

           It is possible to include a sign for all elements that is output.
           See the configuration variable DeltaSigns below.

           NOTE: The internal format of the delta changed in version 5.30 from
           Y:M:D:H:MN:S to Y:M:W:D:H:MN:S .  Also, it is going to change again
           at some point in the future to Y:M:W:D:H:MN:S*FLAGS .  Use the
           routine Delta_Format to extract information rather than parsing it

            @str = Delta_Format($delta [,$mode], $dec,@format);
            $str = Delta_Format($delta [,$mode], $dec,@format);

           This is similar to the UnixDate routine except that it extracts
           information from a delta.  Unlike the UnixDate routine, most of the
           formats are 2 characters instead of 1.

           Formats currently understood are:

              %Xv     : the value of the field named X
              %Xd     : the value of the field X, and all smaller fields, expressed in
                        units of X
              %Xh     : the value of field X, and all larger fields, expressed in units
                        of X
              %Xt     : the value of all fields expressed in units of X

              X is one of y,M,w,d,h,m,s (case sensitive).

              %%      : returns a "%"

           So, the format "%hd" means the values of H, MN, and S expressed in
           hours.  So for the delta "0:0:0:0:2:30:0", this format returns 2.5.

           Delta_Format can operate in two modes: exact and approximate. The
           exact mode is done by default. Approximate mode can be done by
           passing in the string "approx" as the 2nd argument.

           In exact mode, Delta_Format only understands "exact" relationships.
           This means that there can be no mixing of the Y/M and W/D/H/MN/S
           segments because the relationship because, depending on when the
           delta occurs, there is no exact relation between the number of
           years or months and the number of days.

           The two sections are treated completely separate from each other.
           So, the delta "1:6:1:2:12:0:0" would return the following values:

             %yt = 1.5 (1 year, 6 months)
             %Mt = 18

             %dt = 9.5 (1 week, 2 days, 12 hours)

           In approximate mode, the relationship of 1 year = 365.25 days is
           applied (with 1 month equal to 1/12 of a year exactly). So the
           delta "1:6:1:2:12:0:0" would return the following values:

             %dt = 557.375 (1.5 years of 365.25 days + 9.5 days)

           If $dec is non-zero, the %Xd and %Xt values are formatted to
           contain $dec decimal places.

            $recur = ParseRecur($string [,$base,$date0,$date1,$flags]);
            @dates = ParseRecur($string [,$base,$date0,$date1,$flags]);

           A recurrence refers to a recurring event, and more specifically, an
           event which occurs on a regular basis.  A fully specified recurring
           event may requires up to four pieces of information.

           First, it requires a description of the frequency of the event.
           Examples include "the first of every month", "every other day",
           "the 4th Thursday of each month at 2:00 PM", and "every 2 hours and
           30 minutes".

           Second, it may require a base date to work from.  This piece of
           information is not required for every type of recurrence.  For
           example, if the frequency is "the first of every month", no base
           date is required.  All the information about when the event occurs
           is included in the frequency description.  If the frequency were
           "every other day" though, you need to know at least one day on
           which the event occurred.

           Third, the recurring event may have a range (a starting and ending

           Fourth, there may be some flags included which modify the behavior
           of the above information.

           The fully specified recurrence is written as these 5 pieces of
           information (both a start and end date) as an asterisk separated


           Here, base, date0, and date1 are any strings (which must not
           contain any asterisks) which can be parsed by ParseDate.  flags is
           a comma separated list of flags (described below), and freq is a
           string describing the frequency of the recurring event.

           The syntax of the frequency description is a colon separated list
           of the format Y:M:W:D:H:MN:S (which stand for year, month, week,
           etc.).  One (and only one) of the colons may optionally be replaced
           by an asterisk, or an asterisk may be prepended to the string.  For
           example, the following are all valid frequency descriptions:


           But the following are NOT valid because they contain 2 or more


           If an asterisk is included, values to the left of it refer to the
           number of times that time interval occurs between recurring events.
           For example, if the first part of the recurrence is:


           this says that the recurring event occurs approximately every 1
           year and 2 months.  I say approximately, because elements to the
           right of the asterisk, as well as any flags included in the
           recurrence will affect when the actual events occur.

           If no asterisks are included, then the entire recurrence is of this
           form.  For example,


           refers to an event that occurs every 1 day, 12 hours.

           Values that occur after an asterisk refer to a specific value for
           that type of time element (i.e. exactly as it would appear on a
           calendar or a clock).  For example, if the recurrence ends with:


           then the recurring event occurs at 12:00:00 (noon).

           For example:

             0:0:2:1:0:0:0        every 2 weeks and 1 day
             0:0:0:0:5:30:0       every 5 hours and 30 minutes
             0:0:0:2*12:30:0      every 2 days at 12:30 (each day)

           Values to the right of the asterisk can be listed a single values,
           ranges (2 numbers separated by a dash "-"), or a comma separated
           list of values or ranges.  In most cases, negative values are
           appropriate for the week or day values. -1 stands for the last
           possible value, -2 for the second to the last, etc.

           Some examples are:

             0:0:0:1*2,4,6:0:0    every day at at 2:00, 4:00, and 6:00
             0:0:0:2*12-13:0,30:0 every other day at 12:00, 12:30, 13:00,
                                  and 13:30
             0:1:0*-1:0:0:0       the last day of every month
                                  Dec 1 in 1990 through 1995

           There is no way to express the following with a single recurrence:

             every day at 12:30 and 1:00

           You have to use two recurrences to do this.

           When a non-zero day element occurs to the right of the asterisk, it
           can take on multiple meanings, depending on the value of the month
           and week elements.  It can refer to the day of the week, day of the
           month, or day of the year.  Similarly, if a non-zero week element
           occurs to the right of the asterisk, it actually refers to the nth
           time a certain day of the week occurs, either in the month or in
           the year.

           If the week element is non-zero and the day element is non-zero
           (and to the right of the asterisk), the day element refers to the
           day of the week. It can be any value from 1 to 7 (negative values
           -1 to -7 are also allowed). If you use the ISO 8601 convention, the
           first day of the week is Monday (though Date::Manip can use any day
           as the start of the week by setting the FirstDay config variable).
           So, assuming that you are using the ISO 8601 convention, the
           following examples illustrate day-of-week recurrences:

             0:1*4:2:0:0:0        4th Tuesday (day 2) of every month
             0:1*-1:2:0:0:0       last Tuesday of every month
             0:0:3*2:0:0:0        every 3rd Tuesday (every 3 weeks
                                  on 2nd day of week)
             1:0*12:2:0:0:0       the 12th Tuesday of each year

           If the week element is non-zero, and the day element is zero, the
           day defaults to 1 (i.e. the first day of the week).

             0:1*2:0:0:0:0        the 2nd occurrence of FirstDay
                                  in the year (typically Monday)
             0:1*2:1:0:0:0        the same

           If the week element is zero and the month element is non-zero, the
           day value is the day of the month (it can be from 1 to 31 or -1 to
           -31 counting from the end of the month). If a value of 0 is given,
           it defaults to 1.

             3*1:0:2:12:0:0       every 3 years on Jan 2 at noon
             0:1*0:2:12,14:0:0    2nd of every month at 12:00 and 14:00
             0:1:0*-2:0:0:0       2nd to last day of every month

           If the day given refers to the 29th, 30th, or 31st, in a month that
           does not have that number of days, it is ignored. For example, if
           you ask for the 31st of every month, it will return dates in Jan,
           Mar, May, Jul, etc.  Months with fewer than 31 days will be

           If both the month and week elements are zero, and the year element
           is non-zero, the day value is the day of the year (1 to 365 or 366
           -- or the negative numbers to count backwards from the end of the

             1:0:0*45:0:0:0       45th day of every year

           Specifying a day that doesn't occur in that year silently ignores
           that year. The only result of this is that specifying +366 or -366
           will ignore all years except leap years.

           I realize that this looks a bit cryptic, but after a discussion on
           the CALENDAR mailing list, it appeared like there was no concise,
           flexible notation for handling recurring events.  ISO 8601
           notations were very bulky and lacked the flexibility I wanted.  As
           a result, I developed this notation (based on crontab formats, but
           with much more flexibility) which fits in well with this module.
           Even better, it is able to express every type of recurring event I
           could think of that is used in common life in (what I believe to
           be) a very concise and elegant way.

           If ParseRecur is called in scalar context, it returns a string
           containing a fully specified recurrence (or as much of it as can be
           determined with unspecified fields left blank).  In list context,
           it returns a list of all dates referred to by a recurrence if
           enough information is given in the recurrence.  All dates returned
           are in the range:

             date0 <= date < date1

           The argument $string can contain any of the parts of a full
           recurrence.  For example:


           The only part which is required is the frequency description.  Any
           values contained in $string are overridden or modified by values
           passed in as parameters to ParseRecur.

           NOTE: If a recurrence has a date0 and date1 in it AND a date0 and
           date1 are passed in to the function, both sets of criteria apply.
           If flags are passed in, they override any flags in the recurrence
           UNLESS the flags passed in start with a plus (+) character in which
           case they are appended to the flags in the recurrence.

           NOTE: Base dates are only used with some types of recurrences.  For

             0:0:3*2:0:0:0        every 3rd Tuesday

           requires a base date.  If a base date is specified which doesn't
           match the criteria (for example, if a base date falling on Monday
           were passed in with this recurrence), the base date is moved
           forward to the first relevant date.

           Other dates do not require a base date.  For example:

             0:0*3:2:0:0:0        third Tuesday of every month

           A recurrence written in the above format does NOT provide default
           values for base, date0, or date1.  They must be specified in order
           to get a list of dates.

           A base date is not used entirely.  It is only used to provide the
           parts necessary for the left part of a recurrence.  For example,
           the recurrence:

             1:3*0:4:0:0:0        every 1 year, 3 months on the 4th day of the month

           would only use the year and month of the base date.

           There are a small handful of English strings which can be parsed in
           place of a numerical recur description.  These include:

             every 2nd day [in 1997]
             every 2nd day in June [1997]
             2nd day of every month [in 1997]
             2nd Tuesday of every month [in 1997]
             last Tuesday of every month [in 1997]
             every Tuesday [in 1997]
             every 2nd Tuesday [in 1997]
             every 2nd Tuesday in June [1997]

           Each of these set base, date0, and date1 to a default value (the
           current year with Jan 1 being the base date is the default if the
           year and month are missing).

           The following flags (case insensitive) are understood:

             PDn   : n is 1-7.  Means the previous day n not counting today
             PTn   : n is 1-7.  Means the previous day n counting today
             NDn   : n is 1-7.  Means the next day n not counting today
             NTn   : n is 1-7.  Means the next day n counting today

             FDn   : n is any number.  Means step forward n days.
             BDn   : n is any number.  Means step backward n days.
             FWn   : n is any number.  Means step forward n workdays.
             BWn   : n is any number.  Means step backward n workdays.

             CWD   : the closest work day (using the TomorrowFirst config variable).
             CWN   : the closest work day (looking forward first).
             CWP   : the closest work day (looking backward first).

             NWD   : next work day counting today
             PWD   : previous work day counting today
             DWD   : next/previous work day (TomorrowFirst config) counting today

             EASTER: select easter for this year (the M, W, D fields are ignored
                     in the recur).

           CWD, CWN, and CWP will usually return the same value, but if you
           are starting at the middle day of a 3-day weekend (for example), it
           will return either the first work day of the following week, or the
           last work day of the previous week depending on whether it looks
           forward or backward first.

           All flags are applied AFTER the recurrence dates are calculated,
           and they may move a date outside of the date0 to date1 range.  No
           check is made for this.

           The workday flags do not act exactly the same as a business mode
           calculation.  For example, a date that is Saturday with a FW1 steps
           forward to the first workday (i.e. Monday).

            $flag = Date_Cmp($date1,$date2);

           This takes two dates and compares them.  Almost all dates can be
           compared using the Perl "cmp" command.  The only time this will not
           work is when comparing dates in different time zones.  This routine
           will take that into account.

           NOTE:  This routine currently does little more than use "cmp", but
           once the internal format for storing dates is in place (where time
           zone information is kept as part of the date), this routine will
           become more important.  You should use this routine in preparation
           for that version.

            $d = DateCalc($d1,$d2 [,\$err] [,$mode]);

           This takes two dates, deltas, or one of each and performs the
           appropriate calculation with them.  Dates must be a string that can
           be parsed by ParseDateString.  Deltas must be a string that can be
           parsed by ParseDateDelta.  Two deltas add together to form a third
           delta.  A date and a delta returns a 2nd date.  Two dates return a
           delta (the difference between the two dates).

           Since the two items can be interpreted as either dates or deltas,
           and since many types of dates can be interpreted as deltas (and
           vice versa), it is a good idea to pass the input through ParseDate
           or ParseDateDelta as appropriate. For example, the string
           "09:00:00" can be interpreted either as a date (today at 9:00:00)
           or a delta (9 hours). To avoid unexpected results, avoid calling
           DateCalc as:

             $d = DateCalc("09:00:00",$someothervalue);

           Instead, call it as:

             $d = DateCalc(ParseDate("09:00:00"),$someothervalue);

           to force it to be a date, or:

             $d = DateCalc(ParseDateDelta("09:00:00"),$someothervalue);

           to force it to be a delta. This will avoid unexpected results.

           Note that in many cases, it is somewhat ambiguous what the delta
           actually refers to.  Although it is ALWAYS known how many months in
           a year, hours in a day, etc., it is NOT known (in the generals
           case) how many days are in a month.  As a result, the part of the
           delta containing month/year and the part with sec/min/hr/day must
           be treated separately.  For example, "Mar 31, 12:00:00" plus a
           delta of 1month 2days would yield "May 2 12:00:00".  The year/month
           is first handled while keeping the same date.  Mar 31 plus one
           month is Apr 31 (but since Apr only has 30 days, it becomes Apr
           30).  Apr 30 + 2 days is May 2.  As a result, in the case where two
           dates are entered, the resulting delta can take on two different
           forms.  By default ($mode=0), an absolutely correct delta (ignoring
           daylight saving time) is returned in weeks, days, hours, minutes,
           and seconds.

           If $mode is 1, the math is done using an approximate mode where a
           delta is returned using years and months as well.  The year and
           month part is calculated first followed by the rest.  For example,
           the two dates "Mar 12 1995" and "Apr 13 1995" would have an exact
           delta of "31 days" but in the approximate mode, it would be
           returned as "1 month 1 day".  Also, "Mar 31" and "Apr 30" would
           have deltas of "30 days" or "1 month" (since Apr 31 doesn't exist,
           it drops down to Apr 30).  Approximate mode is a more human way of
           looking at things (you'd say 1 month and 2 days more often then 33
           days), but it is less meaningful in terms of absolute time.  In
           approximate mode $d1 and $d2 must be dates.  If either or both is a
           delta, the calculation is done in exact mode.

           If $mode is 2, a business mode is used.  That is, the calculation
           is done using business days, ignoring holidays, weekends, etc.  In
           order to correctly use this mode, a config file must exist which
           contains the section defining holidays (see documentation on the
           config file below).  The config file can also define the work week
           and the hours of the work day, so it is possible to have different
           config files for different businesses.

           For example, if a config file defines the workday as 08:00 to
           18:00, a work week consisting of Mon-Sat, and the standard
           (American) holidays, then from Tuesday at 12:00 to the following
           Monday at 14:00 is 5 days and 2 hours.  If the "end" of the day is
           reached in a calculation, it automatically switches to the next
           day.  So, Tuesday at 12:00 plus 6 hours is Wednesday at 08:00
           (provided Wed is not a holiday).  Also, a date that is not during a
           workday automatically becomes the start of the next workday.  So,
           Sunday 12:00 and Monday at 03:00 both automatically becomes Monday
           at 08:00 (provided Monday is not a holiday).  In business mode, any
           combination of date and delta may be entered, but a delta should
           not contain a year or month field (weeks are fine though).

           See Date::Manip::Calc for some additional comments about business
           mode calculations.

           Note that a business week is treated the same as an exact week
           (i.e. from Tuesday to Tuesday, regardless of holidays).  Because
           this means that the relationship between days and weeks is NOT
           unambiguous, when a delta is produced from two dates, it will be in
           terms of d/h/mn/s (i.e. no week field).

           If $mode is 3 (which only applies when two dates are passed in), an
           exact business mode is used.  In this case, it returns a delta as
           an exact number of business days/hours/etc. between the two.
           Weeks, months, and years are ignored.

           Any other non-nil value of $mode is treated as $mode=1 (approximate

           The mode can be automatically set in the dates/deltas passed by
           including a key word somewhere in it.  For example, in English, if
           the word "approximately" is found in either of the date/delta
           arguments, approximate mode is forced.  Likewise, if the word
           "business" or "exactly" appears, business/exact mode is forced (and
           $mode is ignored).  So, the two following are equivalent:

              $date = DateCalc("today","+ 2 business days",\$err);
              $date = DateCalc("today","+ 2 days",\$err,2);

           Note that if the keyword method is used instead of passing in
           $mode, it is important that the keyword actually appear in the
           argument passed in to DateCalc.  The following will NOT work:

              $delta = ParseDateDelta("+ 2 business days");
              $today = ParseDate("today");
              $date = DateCalc($today,$delta,\$err);

           because the mode keyword is removed from a date/delta by the parse
           routines, and the mode is reset each time a parse routine is
           called.  Since DateCalc parses both of its arguments, whatever mode
           was previously set is ignored.

           If \$err is passed in, it is set to:
              1 is returned if $d1 is not a delta or date
              2 is returned if $d2 is not a delta or date
              3 is returned if the date is outside the years 1000 to 9999 This
           argument is optional, but if included, it must come before $mode.

           Nothing is returned if an error occurs.

           When a delta is returned, the signs such that it is strictly
           positive or strictly negative ("1 day - 2 hours" would never be
           returned for example).  The only time when this cannot be enforced
           is when two deltas with a year/month component are entered.  In
           this case, only the signs on the day/hour/min/sec part are

            $date = Date_SetTime($date,$hr,$min,$sec);
            $date = Date_SetTime($date,$time);

           This takes a date (any string that may be parsed by
           ParseDateString) and sets the time in that date.  For example, one
           way to get the time for 7:30 tomorrow would be to use the lines:

              $date = ParseDate("tomorrow");
              $date = Date_SetTime($date,"7:30");

           Note that in this routine (as well as the other routines below
           which use a time argument), no real parsing is done on the times.
           As a result,

              $date = Date_SetTime($date,"13:30");

           works, but

              $date = Date_SetTime($date,"1:30 PM");


            $date = Date_SetDateField($date,$field,$val [,$nocheck]);

           This takes a date and sets one of its fields to a new value.
           $field is any of the strings "y", "m", "d", "h", "mn", "s" (case
           insensitive) and $val is the new value.

           If $nocheck is non-zero, no check is made as to the validity of the

            $date = Date_GetPrev($date,$dow, $curr [,$hr,$min,$sec]);
            $date = Date_GetPrev($date,$dow, $curr [,$time]);
            $date = Date_GetPrev($date,undef,$curr,$hr,$min,$sec);
            $date = Date_GetPrev($date,undef,$curr,$time);

           This takes a date (any string that may be parsed by
           ParseDateString) and finds the previous occurrence of either a day
           of the week, or a certain time of day.

           If $dow is defined, the previous occurrence of the day of week is
           returned.  $dow may either be a string (such as "Fri" or "Friday")
           or a number (between 1 and 7).  The date of the previous $dow is

           If $date falls on the day of week given by $dow, the date returned
           depends on $curr.  If $curr is 0, the date returned is a week
           before $date.  If $curr is 1, the date returned is the same as
           $date.  If $curr is 2, the date returned (including the time
           information) is required to be before $date.

           If a time is passed in (either as separate hours, minutes, seconds
           or as a time in HH:MM:SS or HH:MM format), the time on this date is
           set to it.  The following examples should illustrate the use of

               date                   dow    curr  time            returns
               Fri Nov 22 18:15:00    Thu    any   12:30           Thu Nov 21 12:30:00
               Fri Nov 22 18:15:00    Fri    0     12:30           Fri Nov 15 12:30:00
               Fri Nov 22 18:15:00    Fri    1/2   12:30           Fri Nov 22 12:30:00

               Fri Nov 22 18:15:00    Fri    1     18:30           Fri Nov 22 18:30:00
               Fri Nov 22 18:15:00    Fri    2     18:30           Fri Nov 15 18:30:00

           If $dow is undefined, then a time must be entered, and the date
           returned is the previous occurrence of this time.  If $curr is non-
           zero, the current time is returned if it matches the criteria
           passed in.  In other words, the time returned is the last time that
           a digital clock (in 24 hour mode) would have displayed the time you
           passed in.  If you define hours, minutes and seconds default to 0
           and you might jump back as much as an entire day.  If hours are
           undefined, you are looking for the last time the minutes/seconds
           appeared on the digital clock, so at most, the time will jump back
           one hour.

               date               curr  hr     min    sec      returns
               Nov 22 18:15:00    0/1   18     undef  undef    Nov 22 18:00:00
               Nov 22 18:15:00    0/1   18     30     0        Nov 21 18:30:00
               Nov 22 18:15:00    0     18     15     undef    Nov 21 18:15:00
               Nov 22 18:15:00    1     18     15     undef    Nov 22 18:15:00
               Nov 22 18:15:00    0     undef  15     undef    Nov 22 17:15:00
               Nov 22 18:15:00    1     undef  15     undef    Nov 22 18:15:00

            $date = Date_GetNext($date,$dow, $curr [,$hr,$min,$sec]);
            $date = Date_GetNext($date,$dow, $curr [,$time]);
            $date = Date_GetNext($date,undef,$curr,$hr,$min,$sec);
            $date = Date_GetNext($date,undef,$curr,$time);

           Similar to Date_GetPrev.

            $name = Date_IsHoliday($date);

           This returns undef if $date is not a holiday, or a string
           containing the name of the holiday otherwise.  An empty string is
           returned for an unnamed holiday.

            $ref = Events_List($date);
            $ref = Events_List($date ,0      [,$flag]);
            $ref = Events_List($date0,$date1 [,$flag]);

           This returns a list of events.  Events are defined in the Events
           section of the config file (discussed below).

           In the first form (a single argument), $date is any string
           containing a date.  A list of events active at that precise time
           will be returned.  The format is similar to when $flag=0, except
           only a single time will be returned.

           In all other cases, a range of times will be used.  If the 2nd
           argument evaluates to 0, the range of times will be the 24 hour
           period from midnight to midnight containing $date.  Otherwise, the
           range is given by the two dates.

           The value of $flag determines the format of the information that is

           With $flag=0, the events are returned as a reference to a list of
           the form:

             [ date, [ list_of_events ], date, [ list_of_events ], ... ]

           For example, if the following events are defined (using the syntax
           discussed below in the description of the Event section of the
           config file):

             2000-01-01 ; 2000-03-21  = Winter
             2000-03-22 ; 2000-06-21  = Spring
             2000-02-01               = Event1
             2000-05-01               = Event2
             2000-04-01-12:00:00      = Event3

           might result in the following output:

              => [ 2000040100:00:00, [ Spring ] ]

             Events_List("2000-04-01 12:30");
              => [ 2000040112:30:00, [ Spring, Event3 ] ]

              => [ 2000040100:00:00, [ Spring ],
                   2000040112:00:00, [ Spring, Event3 ],
                   2000040113:00:00, [ Spring ] ]

              => [ 2000031500:00:00, [ Winter ],
                   2000032200:00:00, [ Spring ]
                   2000040112:00:00, [ Spring, Event3 ]
                   2000040113:00:00, [ Spring ] ]

           Much more complicated events can be defined using recurrences.

           When $flag is non-zero, the format of the output is changed.  If
           $flag is 1, then a tally of the amount of time given to each event
           is returned.  Time for which two or more events apply is counted
           for both.

              => { Winter => +0:0:1:0:0:0:0,
                   Spring => +0:0:2:5:0:0:0,
                   Event3 => +0:0:0:0:1:0:0 }

           When $flag is 2, a more complex tally with no event counted twice
           is returned.

              => { Winter => +0:0:1:0:0:0:0,
                   Spring => +0:0:2:4:23:0:0,
                   Event3+Spring => +0:0:0:0:1:0:0 }

           The hash contains one element for each combination of events.

            $day = Date_DayOfWeek($m,$d,$y);

           Returns the day of the week (1 for Monday, 7 for Sunday).

           All arguments must be numeric.

            $secs = Date_SecsSince1970($m,$d,$y,$h,$mn,$s);

           Returns the number of seconds since Jan 1, 1970 00:00 (negative if
           date is earlier).

           All arguments must be numeric.

            $secs = Date_SecsSince1970GMT($m,$d,$y,$h,$mn,$s);

           Returns the number of seconds since Jan 1, 1970 00:00 GMT (negative
           if date is earlier).  If CurrTZ is "IGNORE", the number will be
           identical to Date_SecsSince1970 (i.e. the date given will be
           treated as being in GMT).

           All arguments must be numeric.

            $days = Date_DaysSince1BC($m,$d,$y);

           Returns the number of days since Dec 31, 1BC.  This includes the
           year 0000.

           All arguments must be numeric.

            $day = Date_DayOfYear($m,$d,$y);

           Returns the day of the year (001 to 366)

           All arguments must be numeric.

            ($y,$m,$d,$h,$mn,$s) = Date_NthDayOfYear($y,$n);

           Returns the year, month, day, hour, minutes, and decimal seconds
           given a floating point day of the year.

           All arguments must be numeric.  $n must be greater than or equal to
           1 and less than 366 on non-leap years and 367 on leap years.

           NOTE: When $n is a decimal number, the results are non-intuitive
           perhaps.  Day 1 is Jan 01 00:00.  Day 2 is Jan 02 00:00.
           Intuitively, you might think of day 1.5 as being 1.5 days after Jan
           01 00:00, but this would mean that Day 1.5 was Jan 02 12:00 (which
           is later than Day 2).  The best way to think of this function is a
           time line starting at 1 and ending at 366 (in a non-leap year).  In
           terms of a delta, think of $n as the number of days after Dec 31
           00:00 of the previous year.

            $days = Date_DaysInYear($y);

           Returns the number of days in the year (365 or 366)

            $days = Date_DaysInMonth($m,$y);

           Returns the number of days in the month.

            $wkno = Date_WeekOfYear($m,$d,$y,$first);

           Figure out week number.  $first is the first day of the week which
           is usually 1 (Monday) or 7 (Sunday), but could be any number
           between 1 and 7 in practice.

           All arguments must be numeric.

           NOTE: This routine should only be called in rare cases.  Use
           UnixDate with the %W, %U, %J, %L formats instead.  This routine
           returns a week between 0 and 53 which must then be "fixed" to get
           into the ISO-8601 weeks from 1 to 53.  A date which returns a week
           of 0 actually belongs to the last week of the previous year.  A
           date which returns a week of 53 may belong to the first week of the
           next year.

            $flag = Date_LeapYear($y);

           Returns 1 if the argument is a leap year Written by David Muir
           Sharnoff <>

            $day = Date_DaySuffix($d);

           Add `st', `nd', `rd', `th' to a date (i.e. 1st, 22nd, 29th).  Works
           for international dates.

            $tz = Date_TimeZone;

           This determines and returns the local time zone.  If it is unable
           to determine the local time zone, the following error occurs:

              ERROR: Date::Manip unable to determine Time Zone.

           See The TIME ZONES section below for more information.

            $date = Date_ConvTZ($date);
            $date = Date_ConvTZ($date,$from);
            $date = Date_ConvTZ($date,"",$to [,$errlev]);
            $date = Date_ConvTZ($date,$from,$to [,$errlev]);

           This converts a date (which MUST be in the format returned by
           ParseDate) from one time zone to another.

           If it is called with no arguments, the date is converted from the
           local time zone to the time zone specified by the config variable
           ConvTZ (see documentation on ConvTZ below).  If ConvTZ is set to
           "IGNORE", no conversion is done.

           If called with $from but no $to, the time zone is converted from
           the time zone in $from to ConvTZ (of TZ if ConvTZ is not set).
           Again, no conversion is done if ConvTZ is set to "IGNORE".

           If called with $to but no $from, $from defaults to ConvTZ (if set)
           or the local time zone otherwise.  Although this does not seem
           immediately obvious, it actually makes sense.  By default, all
           dates that are parsed are converted to ConvTZ, so most of the dates
           being worked with will be stored in that time zone.

           If Date_ConvTZ is called with both $from and $to, the date is
           converted from the time zone $from to $to.

           NOTE: As in all other cases, the $date returned from Date_ConvTZ
           has no time zone information included as part of it, so calling
           UnixDate with the "%z" format will return the time zone that
           Date::Manip is working in (usually the local time zone).

           Example:  To convert 2/2/96 noon PST to CST (regardless of what
           time zone you are in, do the following:

            $date = ParseDate("2/2/96 noon");
            $date = Date_ConvTZ($date,"PST","CST");

           Both time zones MUST be in one of the formats listed below in the
           section TIME ZONES.

           If an error occurs, $errlev determines what happens:

             0   : the program dies
             1   : a warning is produced and nothing is returned
             2   : the function silently returns nothing

             $flag = Date_IsWorkDay($date [,$flag]);

           This returns 1 if $date is a work day.  If $flag is non-zero, the
           time is checked to see if it falls within work hours.  It returns
           an empty string if $date is not valid.

             $date = Date_NextWorkDay($date,$off [,$flag]);

           Finds the day $off work days from now.  If $flag is non-zero, we
           must also take into account the time of day.

           If $flag is zero, day 0 is today (if today is a workday) or the
           next work day if it isn't.  In any case, the time of day is

           If $flag is non-zero, day 0 is now (if now is part of a workday) or
           the start of the very next work day.

             $date = Date_PrevWorkDay($date,$off [,$flag]);

           Similar to Date_NextWorkDay.

             $date = Date_NearestWorkDay($date [,$tomorrowfirst]);

           This looks for the work day nearest to $date.  If $date is a work
           day, it is returned.  Otherwise, it will look forward or backwards
           in time 1 day at a time until a work day is found.  If
           $tomorrowfirst is non-zero (or if it is omitted and the config
           variable TomorrowFirst is non-zero), we look to the future first.
           Otherwise, we look in the past first.  In other words, in a normal
           week, if $date is Wednesday, $date is returned.  If $date is
           Saturday, Friday is returned.  If $date is Sunday, Monday is
           returned.  If Wednesday is a holiday, Thursday is returned if
           $tomorrowfirst is non-nil or Tuesday otherwise.

             $version = DateManipVersion;

           Returns the version of Date::Manip.

       With the release of Date::Manip 6.00, time zones and daylight saving
       time are now fully supported in Date::Manip. 6.00 uses information from
       several standards (most importantly the Olson zoneinfo database) to get
       a list of all known time zones.

       Unfortunately, 6.00 requires a newer version of perl, so I will
       continue to support the 5.xx release for a while. However, the way I
       will support time zones in 5.xx has changed. Previously, new time zones
       would be added on request. That is no longer the case. Time zones for
       5.xx are now generated automatically from those available in 6.00.

       The following time zone names are currently understood (and can be used
       in parsing dates).  These are zones defined in RFC 822.

           Universal:  GMT, UT
           US zones :  EST, EDT, CST, CDT, MST, MDT, PST, PDT
           Military :  A to Z (except J)
           Other    :  +HHMM or -HHMM
           ISO 8601 :  +HH:MM, +HH, -HH:MM, -HH

       In addition, the following time zone abbreviations are also accepted.
       These do not come from a standard, but were included in previous
       releases of Date::Manip 5.xx and are preserved here for backward

          IDLW    -1200    International Date Line West
          NT      -1100    Nome
          SAT     -0400    Chile
          CLDT    -0300    Chile Daylight
          AT      -0200    Azores
          MEWT    +0100    Middle European Winter
          MEZ     +0100    Middle European
          FWT     +0100    French Winter
          GB      +0100    GMT with daylight savings
          SWT     +0100    Swedish Winter
          MESZ    +0200    Middle European Summer
          FST     +0200    French Summer
          METDST  +0200    An alias for MEST used by HP-UX
          EETDST  +0300    An alias for eest used by HP-UX
          EETEDT  +0300    Eastern Europe, USSR Zone 1
          BT      +0300    Baghdad, USSR Zone 2
          IT      +0330    Iran
          ZP4     +0400    USSR Zone 3
          ZP5     +0500    USSR Zone 4
          IST     +0530    Indian Standard
          ZP6     +0600    USSR Zone 5
          AWST    +0800    Australian Western Standard
          ROK     +0900    Republic of Korea
          AEST    +1000    Australian Eastern Standard
          ACDT    +1030    Australian Central Daylight
          CADT    +1030    Central Australian Daylight
          AEDT    +1100    Australian Eastern Daylight
          EADT    +1100    Eastern Australian Daylight
          NZT     +1200    New Zealand
          IDLE    +1200    International Date Line East

       All other time zone abbreviations come from the standards. In many
       cases, an abbreviation may be used for multiple time zones. For
       example, NST stands for Newfoundland Standard -0330 and North Sumatra
       +0630.  In these cases, only 1 of the two is available. I have tried to
       use the most recent definition, and of those (if multiple time zones
       use the abbreviation), the most commonly used. I don't claim that I'm
       correct in all cases, but I've done the best I could.

       The list of abbreviations available is documented in the
       Date::Manip::DM5abbrevs document.

       Date::Manip must be able to determine the time zone the user is in.  It
       does this by looking in the following places:

          $Date::Manip::TZ (set with Date_Init or in
          the Unix `date` command (if available)
          /etc/time zone

       At least one of these should contain a time zone in one of the
       supported forms.  If none do by default, the TZ variable must be set
       with Date_Init.

       The time zone may be in the STD#DST format (in which case both
       abbreviations must be in the table above) or any of the formats
       described above.  The STD#DST format is NOT available when parsing a
       date however.  The following forms are also available and are treated
       similar to the STD#DST forms:


       There are a number of variables which can be used to customize the way
       Date::Manip behaves.  There are also several ways to set these

       At the top of the file, there is a section which contains all
       customization variables.  These provide the default values.

       These can be overridden in a global config file if one is present (this
       file is optional).  If the GlobalCnf variable is set in the
       file, it contains the full path to a config file.  If the file exists,
       its values will override those set in the file.  A sample
       config file is included with the Date::Manip distribution.  Modify it
       as appropriate and copy it to some appropriate directory and set the
       GlobalCnf variable in the file.

       Each user can have a personal config file which is of the same form as
       the global config file.  The variables PersonalCnf and PersonalCnfPath
       set the name and search path for the personal config file.  This file
       is also optional.  If present, it overrides any values set in the
       global file.

       NOTE: if you use business mode calculations, you must have a config
       file (either global or personal) since this is the only place where you
       can define holidays.

       Finally, any variables passed in through Date_Init override all other

       A config file can be composed of several sections.  The first section
       sets configuration variables.  Lines in this section are of the form:

          VARIABLE = VALUE

       For example, to make the default language French, include the line:

          Language = French

       Only variables described below may be used.  Blank lines and lines
       beginning with a pound sign (#) are ignored.  All spaces are optional
       and strings are case insensitive.

       A line which starts with an asterisk (*) designates a new section.  For
       example, the HOLIDAY section starts with a line:


       The various sections are defined below.

       All Date::Manip variables which can be used are described in the
       following section.

           If this variable is used (any value is ignored), the global config
           file is not read.  It must be present in the initial call to
           Date_Init or the global config file will be read.

           If this variable is used (any value is ignored), the current list
           of defined holidays is erased.  A new set will be set the next time
           a config file is read in.  This can be set in either the global
           config file or as a Date_Init argument (in which case holidays can
           be read in from both the global and personal config files) or in
           the personal config file (in which case, only holidays in the
           personal config file are counted).

           This is a regular expression used to separate multiple paths.  For
           example, on Unix, it defaults to a colon (:) so that multiple paths
           can be written PATH1:PATH2 .  For Win32 platforms, it defaults to a
           semicolon (;) so that paths such as "c:\;d:\" will work.

           This variable can be passed into Date_Init to point to a global
           configuration file.  The value must be the complete path to a
           config file.

           By default, no global config file is read.  Any time a global
           config file is read, the holidays are erased.

           Paths may have a tilde (~) expansion on platforms where this is
           supported (currently Unix and VMS).

           This variable can be passed into Date_Init or set in a global
           config file to set the name of the personal configuration file.

           The default name for the config file is .DateManip.cnf on all Unix
           platforms and Manip.cnf on all non-Unix platforms (because some of
           them insist on 8.3 character filenames :-).

           This is a list of paths separated by the separator specified by the
           PathSep variable.  These paths are each checked for the PersonalCnf
           config file.

           Paths may have a tilde (~) expansion on platforms where this is
           supported (currently Unix and VMS).

           Date::Manip can be used to parse dates in many different languages.
           Currently, it is configured to read  the following languages (the
           version in which they added is included for historical interest):

             English      (default)
             French       (5.02)
             Swedish      (5.05)
             German       (5.31)
             Dutch        (5.32)     aka Nederlands
             Polish       (5.32)
             Spanish      (5.33)
             Portuguese   (5.34)
             Romanian     (5.35)
             Italian      (5.35)
             Russian      (5.41)
             Turkish      (5.41)
             Danish       (5.41)

           Others can be added easily.  Language is set to the language used
           to parse dates.  If you are interested in providing a translation
           for a new language, email me (see the AUTHOR section below) and
           I'll send you a list of things that I need.

           Different countries look at the date 12/10 as Dec 10 or Oct 12.  In
           the United States, the first is most common, but this certainly
           doesn't hold true for other countries.  Setting DateFormat to "US"
           forces the first behavior (Dec 10).  Setting DateFormat to anything
           else forces the second behavior (Oct 12).

       TZ  If set, this defines the local time zone.  See the TIME ZONES
           section above for information on its format.

           All date comparisons and calculations must be done in a single time
           zone in order for them to work correctly.  So, when a date is
           parsed, it should be converted to a specific time zone.  This
           allows dates to easily be compared and manipulated as if they are
           all in a single time zone.

           The ConvTZ variable determines which time zone should be used to
           store dates in.  If it is left blank, all dates are converted to
           the local time zone (see the TZ variable above).  If it is set to
           one of the time zones listed above, all dates are converted to this
           time zone.  Finally, if it is set to the string "IGNORE", all time
           zone information is ignored as the dates are read in (in this case,
           the two dates "1/1/96 12:00 GMT" and "1/1/96 12:00 EST" would be
           treated as identical).

           When a date is parsed using ParseDate, that date is stored in an
           internal format which is understood by the Date::Manip routines
           UnixDate and DateCalc.  Originally, the format used to store the
           date internally was:


           It has been suggested that I remove the colons (:) to shorten this


           The main advantage of this is that some databases are colon
           delimited which makes storing a date from Date::Manip tedious.

           In order to maintain backwards compatibility, the Internal variable
           was introduced.  Set it to 0 (to use the old format) or 1 (to use
           the new format).

           It is sometimes necessary to know what day of week is regarded as
           first.  By default, this is set to Monday, but many countries and
           people will prefer Sunday (and in a few cases, a different day may
           be desired).  Set the FirstDay variable to be the first day of the
           week (1=Monday, 7=Sunday) Monday should be chosen to to comply with
           ISO 8601.

       WorkWeekBeg, WorkWeekEnd
           The first and last days of the work week.  By default, Monday and
           Friday.  WorkWeekBeg must come before WorkWeekEnd numerically.  The
           days are numbered from 1 (Monday) to 7 (Sunday).

           There is no way to handle an odd work week of Thu to Mon for
           example or 10 days on, 4 days off.

           If this is non-nil, a work day is treated as being 24 hours long.
           The WorkDayBeg and WorkDayEnd variables are ignored in this case.

       WorkDayBeg, WorkDayEnd
           The times when the work day starts and ends.  WorkDayBeg must come
           before WorkDayEnd (i.e. there is no way to handle the night shift
           where the work day starts one day and ends another).  Also, the
           workday MUST be more than one hour long (of course, if this isn't
           the case, let me know... I want a job there!).

           The time in both can be in any valid time format (including
           international formats), but seconds will be ignored.

           Periodically, if a day is not a business day, we need to find the
           nearest business day to it.  By default, we'll look to "tomorrow"
           first, but if this variable is set to 0, we'll look to "yesterday"
           first.  This is only used in the Date_NearestWorkDay and is easily
           overridden (see documentation for that function).

           Prior to Date::Manip version 5.07, a negative delta would put
           negative signs in front of every component (i.e. "0:0:-1:-3:0:-4").
           By default, 5.07 changes this behavior to print only 1 or two signs
           in front of the year and day elements (even if these elements might
           be zero) and the sign for year/month and day/hour/minute/second are
           the same.  Setting this variable to non-zero forces deltas to be
           stored with a sign in front of every element (including elements
           equal to 0).

           ISO 8601 states that the first week of the year is the one which
           contains Jan 4 (i.e. it is the first week in which most of the days
           in that week fall in that year).  This means that the first 3 days
           of the year may be treated as belonging to the last week of the
           previous year.  If this is set to non-nil, the ISO 8601 standard
           will be ignored and the first week of the year contains Jan 1.

           By default, a 2 digit year is treated as falling in the 100 year
           period of CURR-89 to CURR+10.  YYtoYYYY may be set to any integer N
           to force a 2 digit year into the period CURR-N to CURR+(99-N).  A
           value of 0 forces the year to be the current year or later.  A
           value of 99 forces the year to be the current year or earlier.
           Since I do no checking on the value of YYtoYYYY, you can actually
           have it any positive or negative value to force it into any century
           you want.

           YYtoYYYY can also be set to "C" to force it into the current
           century, or to "C##" to force it into a specific century.  So, in
           1998, "C" forces 2 digit years to be 1900-1999 and "C18" would
           force it to be 1800-1899.

           It can also be set to the form "C####" to force it into a specific
           100 year period.  C1950 refers to 1950-2049.

           If a script is running over a long period of time, the time zone
           may change during the course of running it (i.e. when daylight
           saving time starts or ends).  As a result, parsing dates may start
           putting them in the wrong time zone.  Since a lot of overhead can
           be saved if we don't have to check the current time zone every time
           a date is parsed, by default checking is turned off.  Setting this
           to non-nil will force time zone checking to be done every time a
           date is parsed... but this will result in a considerable
           performance penalty.

           A better solution would be to restart the process on the two days
           per year where the time zone switch occurs.

           If set to 0, use the US character set (7-bit ASCII) to return
           strings such as the month name.  If set to 1, use the appropriate
           international character set.  For example, If you want your French
           representation of December to have the accent over the first "e",
           you'll want to set this to 1.

           This variable can be set to a date in the format:
           YYYY-MM-DD-HH:MN:SS to force the current date to be interpreted as
           this date.  Since the current date is used in parsing, this string
           will not be parsed and MUST be in the format given above.

           If set to a true value (e.g. 1), then "today" will mean the same as
           "midnight today"; otherwise it will mean the same as "now".

       The holiday section of the config file is used to define holidays.
       Each line is of the form:

          DATE = HOLIDAY

       HOLIDAY is the name of the holiday (or it can be blank in which case
       the day will still be treated as a holiday... for example the day after
       Thanksgiving or Christmas is often a work holiday though neither are

       DATE is a string which can be parsed to give a valid date in any year.
       It can be of the form

          Date + Delta
          Date - Delta

       A valid holiday section would be:


          1/1                             = New Year's Day
          third Monday in Feb             = Presidents' Day
          fourth Thu in Nov               = Thanksgiving

          # The Friday after Thanksgiving is an unnamed holiday most places
          fourth Thu in Nov + 1 day       =

          1*0:0:0:0:0:0*EASTER            = Easter
          1*11:0:11:0:0:0*DWD             = Veteran's Day (observed)
          1*0:0:0:0:0:0*EASTER,PD5        = Good Friday

       In a Date + Delta or Date - Delta string, you can use business mode by
       including the appropriate string (see documentation on DateCalc) in the
       Date or Delta.  So (in English), the first workday before Christmas
       could be defined as:

          12/25 - 1 business day          =

       The dates may optionally contain the year.  For example, the dates


       refers to Jan 1 in any year or in only 1999 respectively.  For dates
       that refer to any year, the date must be written such that by simply
       appending the year (separated by spaces) it can be correctly
       interpreted.  This will work for everything except ISO 8601 dates, so
       ISO 8601 dates may not be used in this case.

       Note that the dates are specified in whatever format is set using the
       Date_Init options, so if the standard parsing is D/M/YYYY, you would
       need to specify it as:

          25/12/2002           = Christmas

       In cases where you are interested in business type calculations, you'll
       want to define most holidays using recurrences, since they can define
       when a holiday is celebrated in the financial world.  For example,
       Christmas should be defined as:

          1*12:0:24:0:0:0*FW1  = Christmas

       NOTE: It was pointed out to me that using a similar type recurrence to
       define New Years does not work.  The recurrence:


       fails (worse, it goes into an infinite loop).  The problem is that each
       holiday definition is applied to a specific year and it expects to find
       the holiday for that year.  When this recurrence is applied to the year
       1995, it returns the holiday for 1996 and fails.

       Use the recurrence:



       If you wanted to define both Christmas and Boxing days (Boxing is the
       day after Christmas, and is celebrated in some parts of the world), you
       could do it in one of the following ways:

          1*12:0:24:0:0:0*FW1  = Christmas
          1*12:0:25:0:0:0*FW1  = Boxing

           1*12:0:24:0:0:0*FW1 = Christmas
          01*12:0:24:0:0:0*FW1 = Boxing

          1*12:0:24:0:0:0*FW1   = Christmas
          1*12:0:25:0:0:0*FW1,a = Boxing

       The following examples will NOT work:

          1*12:0:24:0:0:0*FW1  = Christmas
          1*12:0:24:0:0:0*FW2  = Boxing

          1*12:0:24:0:0:0*FW1  = Christmas
          1*12:0:24:0:0:0*FW1  = Boxing

       The reasoning behind all this is as follows:

       Holidays go into affect the minute they are parsed.  So, in the case

          1*12:0:24:0:0:0*FW1  = Christmas
          1*12:0:24:0:0:0*FW2  = Boxing

       the minute the first line is parsed, Christmas is defined as a holiday.
       The second line then steps forward 2 work days (skipping Christmas
       since that's no longer a work day) and define the work day two days
       after Christmas, NOT the day after Christmas.

       An good alternative would appear to be:

          1*12:0:24:0:0:0*FW1  = Christmas
          1*12:0:24:0:0:0*FW1  = Boxing

       This unfortunately fails because the recurrences are currently stored
       in a hash.  Since these two recurrences are identical, they fail (the
       first one is overwritten by the second and in essence, Christmas is
       never defined).

       To fix this, make them unique with either a fake flag (which is

          1*12:0:24:0:0:0*FW1,a  = Boxing

       or adding an innocuous 0 somewhere:

          01*12:0:24:0:0:0*FW1   = Boxing

       The other good alternative would be to make two completely different
       recurrences such as:

          1*12:0:24:0:0:0*FW1  = Christmas
          1*12:0:25:0:0:0*FW1  = Boxing

       At times, you may want to switch back and forth between two holiday
       files.  This can be done by calling the following:


       The Events section of the config file is similar to the Holiday
       section.  It is used to name certain days or times, but there are a few
       important differences:

       Events can be assigned to any time and duration
           All holidays are exactly 1 day long.  They are assigned to a period
           of time from midnight to midnight.

           Events can be based at any time of the day, and may be of any

       Events don't affect business mode calculations
           Unlike holidays, events are completely ignored when doing business
           mode calculations.

       Whereas holidays were added with business mode math in mind, events
       were added with calendar and scheduling applications in mind.

       Every line in the events section is of the form:

          EVENT = NAME

       where NAME is the name of the event, and EVENT defines when it occurs
       and its duration.  An EVENT can be defined in the following ways:


          Date  ; Date
          Date  ; Delta

       Here, Date* refers to a string containing a Date with NO TIME fields
       (Jan 12, 1/1/2000, 2010-01-01) while Date does contain time fields.
       Similarly, Recur* stands for a recurrence with the time fields all
       equal to 0) while Recur stands for a recurrence with at least one non-
       zero time field.

       Both Date* and Recur* refer to an event very similar to a holiday which
       goes from midnight to midnight.

       Date and Recur refer to events which occur at the time given and with a
       duration of 1 hour.

       Events given by "Date ; Date", "Date ; Delta", and "Recur ; Delta"
       contain both the starting date and either ending date or duration.

       Events given as three elements "Date ; Delta ; Delta" or "Recur ; Delta
       ; Delta" take a date and add both deltas to it to give the starting and
       ending time of the event.  The order and sign of the deltas is
       unimportant (and both can be the same sign to give a range of times
       which does not contain the base date).

       The following are not bugs in Date::Manip, but they may give some
       people problems.

       Unable to determine Time Zone
           Perhaps the most common problem occurs when you get the error:

              Error: Date::Manip unable to determine Time Zone.

           Date::Manip tries hard to determine the local time zone, but on
           some machines, it cannot do this (especially non-Unix systems).  To
           fix this, just set the TZ variable, either at the top of the
  file, in the DateManip.cnf file, or in a call to
           Date_Init.  I suggest using the form "EST5EDT" so you don't have to
           change it every 6 months when going to or from daylight saving

           Windows NT does not seem to set the time zone by default.  From the
           Perl-Win32-Users mailing list:

              > How do I get the TimeZone on my NT?
              >      $time_zone = $ENV{'TZ'};
              You have to set the variable before, WinNT doesn't set it by
              default.  Open the properties of "My Computer" and set a SYSTEM
              variable TZ to your time zone.

           This might help out some NT users.

           A minor (false) assumption that some users might make is that since
           Date::Manip passed all of its tests at install time, this should
           not occur and are surprised when it does.

           Some of the tests are time zone dependent.  Since the tests all
           include input and expected output, I needed to know in advance what
           time zone they would be run in.  So, the tests all explicitly set
           the time zone using the TZ configuration variable passed into
           Date_Init.  Since this overrides any other method of determining
           the time zone, Date::Manip uses this and doesn't have to look
           elsewhere for the time zone.

           When running outside the tests, Date::Manip has to rely on its
           other methods for determining the time zone.

       Missing date formats
           Please see the Date::Manip::Problems document for a discussion.

       Complaining about getpwnam/getpwuid
           Another problem is when running on Micro$oft OS's.  I have added
           many tests to catch them, but they still slip through occasionally.
           If any ever complain about getpwnam/getpwuid, simply add one of the

             $ENV{OS} = Windows_NT
             $ENV{OS} = Windows_95

           to your script before

             use Date::Manip

       Date::Manip is slow
           The reasons for this are covered in the SHOULD I USE DATE::MANIP
           section above.

           Some things that will definitely help:

           Version 5.21 does run noticeably faster than earlier versions due
           to rethinking some of the initialization, so at the very least,
           make sure you are running this version or later.

           ISO-8601 dates are parsed first and fastest.  Use them whenever

           Avoid parsing dates that are referenced against the current time
           (in 2 days, today at noon, etc.).  These take a lot longer to

              Example:  parsing 1065 dates with version 5.11 took 48.6 seconds, 36.2
              seconds with version 5.21, and parsing 1065 ISO-8601 dates with version
              5.21 took 29.1 seconds (these were run on a slow, overloaded computer with
              little memory... but the ratios should be reliable on a faster computer).

           Business date calculations are extremely slow.  You should consider
           alternatives if possible (i.e. doing the calculation in exact mode
           and then multiplying by 5/7).  Who needs a business date more
           accurate than "6 to 8 weeks" anyway, right :-)

           Never call Date_Init more than once.  Unless you're doing something
           very strange, there should never be a reason to anyway.

       Sorting Problems
           If you use Date::Manip to sort a number of dates, you must call
           Date_Init either explicitly, or by way of some other Date::Manip
           routine before it is used in the sort.  For example, the following
           code fails:

              use Date::Manip;
              # Date_Init;
              sub sortDate {
                  my($date1, $date2);
                  $date1 = ParseDate($a);
                  $date2 = ParseDate($b);
                  return (Date_Cmp($date1,$date2));
              @dates = ("Fri 16 Aug 96",
                       "Mon 19 Aug 96",
                       "Thu 15 Aug 96");
              @i=sort sortDate @dates;

           but if you uncomment the Date_Init line, it works.  The reason for
           this is that the first time you call Date_Init, it initializes a
           number of items used by Date::Manip.  Some of these have to be
           sorted (regular expressions sorted by length to ensure the longest
           match).  It turns out that Perl has a bug in it which does not
           allow a sort within a sort.  At some point, this should be fixed,
           but for now, the best thing to do is to call Date_Init explicitly.
           The bug exists in all versions up to 5.005 (I haven't tested 5.6.0

           NOTE: This is an EXTREMELY inefficient way to sort data (but read
           the 2nd note below for an easy way to correct this).  Instead, you
           should parse the dates with ParseDate, sort them using a normal
           string comparison, and then convert them back to the format desired
           using UnixDate.

           NOTE: It has been reported to me that you can still use ParseDate
           to sort dates in this way, and be quite efficient through the use
           of Memoize.  Just add the following lines to your code:

              use Date::Manip;
              use Memoize;
              @i=sort sortDate @dates;

           Since sortDate would call ParseDate with the same data over and
           over, this is a perfect application for the Memoize module.  So,
           sorting with ParseDate is no longer slow for sorting.

       RCS Control
           If you try to put Date::Manip under RCS control, you are going to
           have problems.  Apparently, RCS replaces strings of the form
           "$Date...$" with the current date.  This form occurs all over in
           Date::Manip.  To prevent the RCS keyword expansion, checkout files
           using "co -ko".  Since very few people will ever have a desire to
           do this (and I don't use RCS), I have not worried about it.

       Daylight Saving Times
           Date::Manip does not handle daylight saving time, though it does
           handle time zones to a certain extent.  Converting from EST to PST
           works fine.  Going from EST to PDT is unreliable.

           The following examples are run in the winter of the US East coast
           (i.e.  in the EST time zone).

                   print UnixDate(ParseDate("6/1/97 noon"),"%u"),"\n";
                   => Sun Jun  1 12:00:00 EST 1997

           June 1 EST does not exist.  June 1st is during EDT.  It should

                   => Sun Jun  1 00:00:00 EDT 1997

           Even explicitly adding the time zone doesn't fix things (if
           anything, it makes them worse):

                   print UnixDate(ParseDate("6/1/97 noon EDT"),"%u"),"\n";
                   => Sun Jun  1 11:00:00 EST 1997

           Date::Manip converts everything to the current time zone (EST in
           this case).

           Related problems occur when trying to do date calculations over a
           time zone change.  These calculations may be off by an hour.

           Also, if you are running a script which uses Date::Manip over a
           period of time which starts in one time zone and ends in another
           (i.e. it switches form Daylight Saving Time to Standard Time or
           vice versa), many things may be wrong (especially elapsed time).

           These problems will not be fixed in Date::Manip 5.xx. Date::Manip
           6.xx has full support for time zones and daylight saving time.

       Please refer to the Date::Manip::Problems documentation for information
       on submitting bug reports or questions to the author.

       Date::Manip        - main module documentation

       This script is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

       Sullivan Beck (

perl v5.20.0                      2014-09-14             Date::Manip::DM5(3pm)

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