NAME

PerpetualCalendar

EXAMPLE

    #!/usr/local/bin/perl

    use diagnostics;
    use strict;
    use warnings;
    use DateTime::PerpetualCalendar;
    use Getopt::Long;

    my ($year, $month, $mday);
    GetOptions("year=i" => \$year, "month=i" => \$month,
        "mday=i" => \$mday);

    sub usage
    {
        print "USAGE: $0 --year=YYYY --month=MM --mday=DD\n";
        print "example: $0 --year=1972 --month=2 --mday=7";
        print "    (should be Monday)\n";
        exit 0;
    }

    &usage if (!defined($year) or !defined($month) or
               !defined($mday));

    my $result = dow($year, $month, $mday);

    print "Sunday\n" if ($result == 0);
    print "Monday\n" if ($result == 1);
    print "Tuesday\n" if ($result == 2);
    print "Wednesday\n" if ($result == 3);
    print "Thursday\n" if ($result == 4);
    print "Friday\n" if ($result == 5);
    print "Saturday\n" if ($result == 6);

DESCRIPTION

This is another implementation of a perpetual calendar. However, dates prior to October 15, 1582 (the Gregorian Reformation) were not taken into consideration, thus, the day of week for them would be incorrectly reported.

A return value of 0 means that the day of week is "Sunday". A return value of 1 is "Monday", 2 is "Tuesday", 3 is "Wednesday", 4 is "Thursday", 5 is "Friday", and 6 is "Saturday".

REFERENCE

"A Mental Calendar" by Michael Keith, Journal of Recreational Mathematics, 1975-1976.

LICENSE

This program is free software; you can redistribute it or modify it under the terms of the GNU General Public License.

AUTHOR

Julius C. Duque <jcduque (AT) lycos (DOT) com>