Unix timestamp of week numbers

[nico1234]

I want to have the  timestamps  of  week numbers, this is working perfectly from the year 2011 to  2012.  It refuses to switch to the year 2013. 

Do anyone know what i'm doing wrong?:

 

<?php

 

$year='2012';

$weekno='01';

$date = strtotime($year.'W'.$weekno);

 

for($i=0;$i<55;$i++){

        print date('d-m-Y W',$date)."\n";

        $date=(weekno($date,'1'))."\n";

        $date=(int)$date;

}

 

 

function weekno($date,$step=''){

        $year=date('Y',$date);

      $weekno=date('W',$date);

        $date = strtotime($year.'W'.$weekno);

        if($step>0){

                $date = strtotime($year.'W'.$weekno. '+1 week');

        }

        if($step<0){

                $date = strtotime($year.'W'.$weekno. '-1 week');

        }

      return($date);

 

}

 

 

?>

 

 

[xyph]

There's no need to use strtotime(+1 week). You can add or subtract a week from a timestamp using

 

60*60*24*7 or 604800.

 

That's 60 seconds times 60 minutes times 24 hours times 7 days.

 

This can be accomplished much faster using math.

 

<?php

$year='2015';

// Used from http://php.net/manual/en/function.date.php#85332
$stamp = strtotime($year.'W010');

// Determine if the year has 52 or 53 weeks.
// First we calculate the timestamp 53 weeks from the start
$week53 = $stamp + (604800*53);
// We then use the date function to get the week number of that timestamp
$week53num = date( 'W', $week53 );
// If the week number is 53, the year has 53 weeks
if( $week53num == '53' ) {
$max = 53;
// Otherwise, it only has 52
} else {
$max = 52;
}

// We loop through weeks, starting at 0 and ending at either 51, or 52 depending on the value of $max
for( $week = 0; $week < $max; $week++ ) {
// We multiply the number of seconds in a week with the current week number to get the timestamp for that week
$weekstamp = $stamp + ( 604800*$week );
// We use the calculated timestamp in the date function to output the formatted date.
echo 'Week '.($week+1).' is on '.date('d-m-y',$weekstamp).'<br>';
}


?>