<?php

include "Date.php";

$dates = array(
		'2009-09-20 09:10:15',
		'2009-09-21 09:10:15',
		'2009-09-22 09:10:15',
		'2009-09-23 09:10:15',
		'2009-09-24 09:10:15',
		'2009-09-25 09:10:15',
		'2009-09-26 09:10:15',
	);
# requires Date 1.5.0 and above
foreach (array_values($dates) as $datestr) {
	print get_first_day_of_the_week($datestr);
	print "\n";
}

function get_first_day_of_the_week($datestr)
{
	$date = new Date($datestr);
	$dow = $date->getDayOfWeek();
	$date->addDays(-($dow + 6) % 7);
	return $date->format("%Y-%m-%d");
}

?>