Get ISO-8601 week number for a given date in PHP

get_weekth.php

<?php
/**
 * Get ISO-8601 week number for a given date
 *
 * @author	Faisalman <fyzlman@gmail.com>
 * @link	http://gist.github.com/faisalman
 * @link	http://en.wikipedia.org/wiki/ISO_week_date
 * @param $y	int	year
 * @param $m	int	month
 * @param $d	int	day
 * @return	int	week number
 */
function get_weekth($y, $m, $d)
{
	return intval(date('W',strtotime($y.'-'.$m.'-'.$d)));
}
/* 
 * Usage example:
 * echo get_weekth(2010,12,26); // 51
 * echo get_weekth(2011,1,1); // 52
 * echo get_weekth(2011,1,3); // 1
 */
?>