YA: Finding the Saturdays of the Year

<?php
// Response to: http://answers.yahoo.com/question/index?qid=20110911220601AAe0C33


/*        Timestamps are your friends. As well as the php function strtotime();
        http://php.net for more info
*/

// Start with some variables
$day = (60*60*24); // 60 secs * 60 mins * 24 hours
$week = ($day * 7); // a day * 7 days

$startDate = 'April 4, 2011'; // The date you wish to start retrieving weeks from
$getWeekOne = false; // If you are using the first day of the year, you will want to look for week one (true), if you are using another date, set to false.


// First you start with getting the first saturday of the year.
$fSat = (int)strtotime($startDate) + ($day/2); // Returns the timestamp of Jan 1, 2011.
$dayNum = (int)date('w',$fSat); // Returns the day of the week 0 (Sunday) - 6 (Saturday);

if($dayNum !== 6) { // If the day is not a Saturday
    $fSat += $day * (6 - $dayNum); // Add the appropriate Seconds to the timestamp
}
// $fSat is not set to the first Saturday of the year.
// It must now be checked to see if it is in the first ISO-8601 week number. (A week starts on monday).

while((int)date('W', $fSat) !== 1 && $getWeekOne){
    $fSat += $week; // Add A week to the timestamp.
}

/* NOTE: Jan 1, 2011 is a Saturday, but because Monday is the first day of the
week, Jan 1, 2011 is actually week 52 of 2010. So, Week 1 Saturday is the 8th of January. */

$sats = Array();
$cWeek = (int)date('W',$fSat);
while( $cWeek <= 52){
    $sats[] = $cWeek . ': ' . date("D MjS, Y", $fSat);
    $fSat += $week;
    $cWeek++;
}

echo '<pre>';
print_r($sats);

?>