PHP Array of DateTime seems skewed -

i trying create function create array of datetime(s). dates want every saturday in given year.

i have function when values stored in array, begin second saturday of year , extend first saturday of following year.

note following displays list of saturdays generated function , after couple of blank lines displays saturdays store in array.

<?php define ('sql','y-m-d'); define ('br','<br/>');  function allsaturdays ($year){     $endofyear = "$year-12-31";     $interval = new dateinterval("p7d");      $year--;     $workingdate = "$year-12-31";        $workingdate  = strtotime ($workingdate);     $workingdate  = strtotime ("next saturday",$workingdate);       $workingdate  = date ("y-m-d",$workingdate);        $workingdate  = new datetime ($workingdate);      $result[] = new datetime;     while ($workingdate->format(sql) <= $endofyear ) {        $result[] = $workingdate;        echo $workingdate->format (sql).br;             $workingdate->add ($interval);        $workingdate = new datetime ($workingdate->format(sql));        //echo $workingdate->format (sql)."#".br;;     }// while       unset ($workingdate);       return $result;     }//function     $sats = allsaturdays(2016);    echo "<br/.<br/>";   foreach ($sats $saturday)      echo $saturday->format(sql)."*<br>";     ?> 

however, if store date (2016-01-02) correct values in array.

no doubt i'm missing simple. appreciated.

dave

you modifying datetime object after placed in array.

this add array:

$result[] = $workingdate; 

and line after adds 7 days it:

$workingdate->add($interval); 

calling add modifies original. if want make sure you're working on copy, call clone first or use datetimeimmutable instead of datetime.

here's new version of code using datetimeimmutable:

function allsaturdays ($year){      $endofyear = new datetimeimmutable("$year-12-31");     $workingdate = new datetimeimmutable("first saturday of january " . $year);      while ($workingdate <= $endofyear ) {        $result[] = $workingdate;        $workingdate = $workingdate->modify('+7 days');     }// while     return $result;     }//function 

here's version not use datetimeimmutable

function allsaturdays ($year){      $endofyear = new datetime("$year-12-31");     $workingdate = new datetime("first saturday of january " . $year);      while ($workingdate <= $endofyear ) {        $result[] = $workingdate;        $workingdate = clone $workingdate;        $workingdate->modify('+7 days');     }// while     return $result;     }//function