$date = mktime(1, 1, 1, $month, date("d"), $year);
	
	$first_day_of_month = strtotime("-" . (date("d", $date)-1) . " days", $date);
	$last_day_of_month = strtotime("+" . (date("t", $first_day_of_month)-1) . " days", $first_day_of_month);
	
	$first_week_no = date("W", $first_day_of_month);
	$last_week_no = date("W", $last_day_of_month);
	
	if($last_week_no < $first_week_no) $last_week_no=date("W", strtotime("-1 week",$last_week_no)) + 1;
		$weeks_of_month = $last_week_no - $first_week_no + 1;
	return $weeks_of_month;

This is the code i m using but it wont works.this code is written by my senior and there is nobody to help me. If possible can someone help me to understand this?

Hey dude, If you want to find the number of weeks in a year and number of weeks in a month, just use the following code..

<?php
echo date("W", mktime(0,0,0,12,31,2010)); // To find number of weeks in a year

echo "<br />";

echo date("w", mktime(0,0,0,12,31,2010)); // To find number of weeks in a month

echo "<br />";

?>

You're wrong on one thing, according to ISO documentation the good answer is :

echo date("W", mktime(0,0,0,12,28,$year)); // 28 december is always in the last week because weeks are 7 days

your code :

echo date("W", mktime(0,0,0,12,31,$year));

will return 01 for some years because the 31 december is in the first week of the next year

if you wan't more informations about that : http://en.wikipedia.org/wiki/ISO_week_date