php - why the last element of array changed after 2 foreach loop? -

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• strange behavior of foreach 2 answers

what's magic? last element of $data changed, after 2 each loop.

<?php $data = array("1" => "a", "2" => "b"); print_r($data); foreach($data $k=>&$v) {} foreach($data $k=>$v) {} print_r($data); 

output:[2] => after second foreach

array (     [1] =>     [2] => b ) array (     [1] =>     [2] => ) 

it code change this,the array won't change:

<?php foreach($data $k=>&$v) {} foreach($data $k=>&$v) {} 

from foreach manual:

warning reference of $value , last array element remain after foreach loop. recommended destroy unset().

so @ end of first foreach, $v reference last element in array. next foreach's first iteration changes value of $v (to value of first array element) reference last element in array, changed.

$data = array("1" => "a", "2" => "b"); print_r($data); foreach($data $k=>&$v) {} unset($v);                     // *** unset here *** foreach($data $k=>$v) {} print_r($data); 

result:

array (     [1] =>     [2] => b ) array (     [1] =>     [2] => b )