php: issue with Using Reference Arrays -

<?php  $fruits = array(' apple', 'pear3', 'banana--'); $vegetables = array('pea', 'broccoli   '); $processarr = array(&$fruits, &$vegetables); foreach($processarr &$array)     foreach($array &$item)     {         $item = preg_replace('/[^a-z]/i', '', $item);         $item = ucwords(strtolower($item));     } echo '<pre>'; print_r($fruits); print_r($vegetables); 

result:

array (     [0] => apple     [1] => pear     [2] => banana ) array (     [0] => pea     [1] => broccoli ) 

question:

i know 1 $processarr = array(&$fruits, &$vegetables);, means pass reference of $fruits, $vegetables, if $processarr changed, change $fruits, $vegetables, not understand why use & in foreach, can explain me? thanks.

foreach($processarr &$array)         foreach($array &$item) 

& in foreach allows modifying element in array using reference. if not use reference, modify value, have use array keys.

foreach ( $data &$element ) {   $element = $element + 'foo'; } 

equals

foreach ( $data $key => $element ) {   $data[$key] = $element + 'foo'; }