You can pass a variable by reference.
None.
<?php $a = []; $a['name'] = 'apple'; $b =& $a['name']; echo "$b / "; $b = 'banana'; echo $a['name']; function assign(&$to, $str) { // $to is a reference variable $to = $str; } assign($a['name'], 'lemon'); echo " / $b";
apple / banana / lemon