# CODE:
$arr = array(“0001”, “2”, “03”, “00004”);
usort($arr, ‘compare_length’);

var_dump($arr);

# OUTPUT
array(4) {
[0]=>
string(1) “2”
[1]=>
string(2) “03”
[2]=>
string(4) “0001”
[3]=>
string(5) “00004”
}

function compare_length($s1, $s2) {
$l1 = strlen($s1);
$l2 = strlen($s2);
if ($l1 == $l2) return 0;
return ($l1 < $l2) ? -1 : 1; }