Online PHP editor | output for q3MhC

<?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);