<?php
$x = [1,2,3];
foreach($x as &$ref){
$ref += 100;
}
/* $x === [101, 102, 103]
at this point, $ref is bound to the last element of $x, that's OK
*/
$b = $x;
/* this should logically copy $x to $b *by value* (COW happens) */
$b[0] = 0; /* this should force an array copy in memory */
/* here, $ref should be rebound to the elements of $x by reference
*/
foreach($x as &$ref){
$ref += 100;
}
/* at this point, $x === [201, 202, 203] which is correct, $ref
refers
to the last element of $x again, which is OK,
BUT! As we copied $b by value before, is should stay as is, but the
last
element of $b changes to 203! */
var_dump($b);