data67 has asked for the wisdom of the Perl Monks concerning the following question:

Description
I have been looking at this php code that calculates US holidays. I have been trying to translate this into perl for me to use this in a portion of my application. I was wondering if someone could help me translate the following piece.

Piece Needed to translate

if (!$week || ($week == "")) {
     $lastday = date("t", mktime(0,0,0,$month,1,$year));
     $temp = (date("w",mktime(0,0,0,$month,$lastday,$year)) - $day_of_
+week) % 7;
} else {
     $temp = ($day_of_week - date("w",mktime(0,0,0,$month,1,$year))) %
+ 7;
}

[download]

As you can see the too main things that need to be replaced are the "date" and "mktime" fuction.

Thanks in advance for your help :-)


For anyone interested in the whole code

#!/usr/local/bin/perl -w

use CGI;
use POSIX;
use Date::Calc qw(:all);
#use diagnostics;

# Code taken from 
# http://abledesign.com/programs/holiday_code.php
# US Holiday Calculations in PHP
# Version 1.02
# by Dan Kaplan <design@abledesign.com>
#

#($year,$month,$day) = Today();
($y) = Today();                               # Get current year

# format to use:
#
# get_holiday("year", "month", "day_of_week", "week_of_month");
# get_holiday("year", "month", "day_of_week");    # no 4th field indic
+ates last week of month check
# format_date("year", "month", "day");

print "<p><b>$y Holidays</b></p>";
print "<ul>";

print "<li>New Year's Day = ". format_date($y, 1, 1);
print "<br>New Year's Day Observed = ". observed_day($y, 1, 1);
print "<li>Martin Luther King Day Observed (Third Monday in January) =
+ ". &get_holiday($y, 1, 1, 3);
print "<li>Valentine's Day = ". format_date($y, 2, 14);
print "<li>President's Day Observed (Third Monday in February) = ". &g
+et_holiday($y, 2, 1, 3);
print "<li>St. Patrick's Day = ". format_date($y, 3, 17);
print "<li>Easter = ". calculate_easter($y);
print "<li>Cinco De Mayo = ". format_date($y, 5, 5);
print "<li>Memorial Day Observed (Last Monday in May) = ". &get_holida
+y($y, 5, 1, "");
print "<li>Independence Day = ". format_date($y, 7, 4);
print "<br>Independence Day Observed = ". observed_day($y, 7, 4);
print "<li>Labor Day Observed (First Monday in September) = ". &get_ho
+liday($y, 9, 1, 1);
print "<li>Columbus Day Observed (Second Monday in October) = ". &get_
+holiday($y, 10, 1, 2);
print "<li>Halloween = ". format_date($y, 10, 31);

# Veteran's Day Observed - November 11th ?
print "<li>Thanksgiving (Fourth Thursday in November) = ". &get_holida
+y($y, 11, 4, 4);
print "<li>Christmas Day = ". format_date($y, 12, 25);
print "</ul>";

exit(0);

sub format_date {
        my ($year, $month, $day) = @_;

        # pad single digit months/days with a leading zero for consist
+ency (aesthetics)
        # and format the date as desired: YYYY-MM-DD by default

        if (length($month) == 1) {
                $month = "0$month";
        }
        if (length($day) == 1) {
                $day = "0$day";
        }

        $date = "$year$month$day";
        return $date;
}


# the following function get_holiday() is based on the work done by
# Marcos J. Montes: http:#www.smart.net/~mmontes/ushols.html
# if $week is not passed in, then we are checking for the last week of
+ the month
sub get_holiday {
        my ($year, $month, $day_of_week, $week) = @_;

        if ( (($week ne "") && (($week > 5) || ($week < 1))) || ($day_
+of_week > 6) || ($day_of_week < 0) ) {
                # $day_of_week must be between 0 and 6 (Sun=0, ... Sat
+=6);
                # $week must be between 1 and 5
                return;
        } else {
                #if (!$week || ($week == "")) {
                #       $lastday = date("t", mktime(0,0,0,$month,1,$ye
+ar));
                #       $temp = (date("w",mktime(0,0,0,$month,$lastday
+,$year)) - $day_of_week) % 7;
                #} else {
                #       $temp = ($day_of_week - date("w",mktime(0,0,0,
+$month,1,$year))) % 7;
                #}

                if (!$week || ($week == "")) {
                        $lastday = date("t", mktime(0,0,0,$month,1,$ye
+ar));
                        $temp = (date("w",mktime(0,0,0,$month,$lastday
+,$year)) - $day_of_week) % 7;
                } else {
                        $temp = ($day_of_week - date("w",mktime(0,0,0,
+$month,1,$year))) % 7;
                }


                if ($temp < 0) {
                        $temp += 7;
                }

                if (!$week || ($week == "")) {
                        $day = $lastday - $temp;
                } else {
                        $day = (7 * $week) - 6 + $temp;
                }

                return format_date($year, $month, $day);
        }
}

sub observed_day {
        my ($year, $month, $day) = @_;

        # sat -> fri & sun -> mon, any exceptions?
        #
        # should check $lastday for bumping forward and $firstday for 
+bumping back,
        # although New Year's & Easter look to be the only holidays th
+at potentially
        # move to a different month, and both are accounted for.


        $dow = date("w", mktime(0, 0, 0, $month, $day, $year));
        if ($dow == 0) {
                $dow = $day + 1;
        } elsif ($dow == 6) {
                if (($month == 1) && ($day == 1)) {    # New Year's on
+ a Saturday
                        $year--;
                        $month = 12;
                        $dow = 31;
                } else {
                        $dow = $day - 1;
                }
        } else {
                $dow = $day;
        }

        return format_date($year, $month, $dow);
}

sub calculate_easter {
        my ($y) = @_;

        # In the text below, 'intval($var1/$var2)' represents an integ
+er division neglecting
        # the remainder, while % is division keeping only the remainde
+r. So 30/7=4, and 30%7=2
        #
        # This algorithm is from Practical Astronomy With Your Calcula
+tor, 2nd Edition by Peter
        # Duffett-Smith. It was originally from Butcher's Ecclesiastic
+al Calendar, published in
        # 1876. This algorithm has also been published in the 1922 boo
+k General Astronomy by
        # Spencer Jones; in The Journal of the British Astronomical As
+sociation (Vol.88, page
        # 91, December 1977); and in Astronomical Algorithms (1991) by
+ Jean Meeus.

        $a = $y%19;
        $b = intval($y/100);
        $c = $y%100;
        $d = intval($b/4);
        $e = $b%4;
        $f = intval(($b+8)/25);
        $g = intval(($b-$f+1)/3);
        $h = (19*$a+$b-$d-$g+15)%30;
        $i = intval($c/4);
        $k = $c%4;
        $l = (32+2*$e+2*$i-$h-$k)%7;
        $m = intval(($a+11*$h+22*$l)/451);
        $p = ($h+$l-7*$m+114)%31;
        $EasterMonth = intval(($h+$l-7*$m+114)/31);    # [3 = March, 4
+ = April]
        $EasterDay = $p+1;    # (day in Easter Month)

        return format_date($y, $EasterMonth, $EasterDay);
}

[download]

Replies are listed 'Best First'.
Re: Perl from PHP
by cbro (Pilgrim) on May 08, 2003 at 14:54 UTC 
    $lastday = date("t", mktime(0,0,0,$month,1,$year));
$temp = (date("w",mktime(0,0,0,$month,$lastday,
               $year)) - $day_of_week) % 7;

    [download]
    The first line is returning the number of days in the given month. The second line is the day of the week.
    Date::Calc has the functions:
    Days_in_Month($year, $month)
    Day_of_Week($year,$month,$day)

    Maybe those two functions, or at least something from Date::Calc, will help you. ust do perldoc Date::Calc for more details.
    HTH,
    Chris
[reply]
[d/l]
Re: Perl from PHP
by Thelonius (Priest) on May 08, 2003 at 15:06 UTC
    mktime is a POSIX function, so you can use POSIX::mktime. Although you can (probably should) use one of the Date modules from CPAN, here are a couple of brief functions:
    sub dayofweek {
  # 0=Sunday .. 6=Saturday
  # input is Unix epoch time
  return (4 + int($_[0]/86400)) % 7;
}

sub daysinmonth {
  # input is Unix epoch time
  my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
      localtime($_[0]);
  if (++$mon == 12) {
    $mon = 0;
    $year++;
  }
  ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) =
      localtime(POSIX::mktime(0,0,0,1,$mon,$year) - 3600*3);
  return $mday;
}

    [download]
    Update:Errr, don't use the day of week function. It gives the day of week all right--in London (gmtime)! Here's an even simpler function that works with your time zone:
    sub dayofweek { (localtime $_[0])[6] }

    [download]
    Duh.
[reply]
[d/l]
[select]
Re: Perl from PHP
by tcf22 (Priest) on May 08, 2003 at 14:54 UTC
    Check out Time::Local. This does the opposite of localtime, so you can get the day of week, etc. 
    use Time::Local;
my $time = timelocal($sec,$min,$hour,$mday,$mon,$year);
my @time_array = localtime($time);

    [download]
    As for 
    date("t", mktime(0,0,0,$month,1,$year));

    [download]
    I think you may have to just make an array with the last days of every month and use $lastdays[$mon] to get that day. I'm not aware of a perl function that will do that.
[reply]
[d/l]
[select]
Re: Perl from PHP
by jepri (Parson) on May 09, 2003 at 04:05 UTC
    And here is the pretty much obligatory comment that Date::Manip can do pretty much everything that you want, even calculate when Easter is.

    ____________________
    Jeremy
    I didn't believe in evil until I dated it.

[reply]

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