Can someone explain this to me?

why.php

<?php
$array = array(0,1,2,3);

foreach ($array as &$val) {
    $val = $val + 1;
}
print_r($array);

foreach ($array as $foo) {
    echo $foo;
}
echo "\n";

foreach ($array as $val) {
    echo $val;
}
echo "\n";

/* Output:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
)
1234
1233
   ^ ?????

*/

Here's the answer: http://stackoverflow.com/questions/8220399/php-foreach-pass-by-reference-last-element-duplicating-bug