PHP foreach issue

php_foreach.php

<?php 
$arr = range(1,3);
var_dump($arr);

print("<br>");
foreach($arr as &$val) {
    var_dump($arr);
    var_dump($val);
    print("<br>");
}

print("<br>");
foreach($arr as $val) {
    var_dump($arr);
    var_dump($val);
    print("<br>");
}

unset($val);
print("<br>");
var_dump($arr);

print("<br>");
print("<br>");
foreach($arr as $val) {
    var_dump($arr);
    var_dump($val);
    print("<br>");
}

array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(3) }
array(3) { [0]=> &int(1) [1]=> int(2) [2]=> int(3) } int(1)
array(3) { [0]=> int(1) [1]=> &int(2) [2]=> int(3) } int(2)
array(3) { [0]=> int(1) [1]=> int(2) [2]=> &int(3) } int(3)

array(3) { [0]=> int(1) [1]=> int(2) [2]=> &int(1) } int(1)
array(3) { [0]=> int(1) [1]=> int(2) [2]=> &int(2) } int(2)
array(3) { [0]=> int(1) [1]=> int(2) [2]=> &int(2) } int(2)

array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(2) }

array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(2) } int(1)
array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(2) } int(2)
array(3) { [0]=> int(1) [1]=> int(2) [2]=> int(2) } int(2)

refer http://www.laruence.com/2008/11/20/630.html