====
#!/usr/bin/env perl

#use 5.012;
use strict;
use warnings;

use DateTime;
use Time::Local;

my $dt = DateTime->new(year => 2016, month => 1, day => 1);

print "DateTIme confirms that 01-01-2016 was a => " . $dt->day_name . "\n";
print "DateTime return the Week no for 01-01-2016 => " . $dt->week . "\n";

$dt = DateTime->new(year => 2016, month => 1, day => 4);
print "DateTIme confirms that 04-01-2016 was a => " . $dt->day_name . "\n";
print "DateTime return the Week no for 04-01-2016 => " . $dt->week . "\n";

my ($MONTHDAY, $WEEKDAY, $YEARDAY) = (localtime (timelocal(0,0,0,1,0,2016)))[3,6,7];
my $WEEKNUM = int($YEARDAY / 7) + 1;

print "using localtime to calculate weekno (01/01/2016) => " . $WEEKNUM . "\n";

($MONTHDAY, $WEEKDAY, $YEARDAY) = (localtime (timelocal(0,0,0,4,0,2016)))[3,6,7];
$WEEKNUM = int($YEARDAY / 7) + 1;

print "using localtime to calculate weekno (04/01/2016) => " . $WEEKNUM . "\n";

print "UNIX system cal command output for 1st month \n";
system("cal -w 1 2016");
===