Get the weeks list between 2 dates

Get the weeks list between 2 dates

I am trying to get list of weeks between 2 dates to be like (1st week
May-2013,2nd week may-2003,.....);
I tried a lot of example with no luck.
here is my code until now
function days_between($datefrom,$dateto){
$fromday_start =
mktime(0,0,0,date("m",$datefrom),date("d",$datefrom),date("Y",$datefrom));
$diff = $dateto - $datefrom;
$days = intval( $diff / 86400 ); // 86400 / day
if( ($datefrom - $fromday_start) + ($diff % 86400) > 86400 )
$days++;
return $days;
}
function weeks_between($datefrom, $dateto)
{
$day_of_week = date("w", $datefrom);
echo $days_of_week."<br />";
$fromweek_start = $datefrom - ($day_of_week * 86400) - ($datefrom %
86400);
echo $fromweek_start."<br />";
$diff_days = days_between($datefrom, $dateto);
echo $diff_days."<br />";
$diff_weeks = intval($diff_days / 7);
echo $diff_weeks."<br />";
$seconds_left = ($diff_days % 7) * 86400;
if( ($datefrom - $fromweek_start) + $seconds_left > 604800 )
$diff_weeks ++;
return $diff_weeks;
}
echo weeks_between($_POST[Datepicker1], $_POST[Datepicker1]);// 21
any suggestion