<?php
// improved sort algorithm
// Possible BC break: mixed data types can yield different results
// PHP 5: array(6) {[0]=> string(1) "4", [1]=> int(4), [2]=> string(1) "5", [3]=> int(5)}
// PHP 7: array(6) {[0]=> int(4), [1]=> string(1) "4", [2]=> int(5), [3]=> string(1) "5"}
$a = [4, 5, '4', '5'];
sort($a);
var_dump($a);
array(4) { [0]=> int(4) [1]=> string(1) "4" [2]=> int(5) [3]=> string(1) "5" }SOURCE CODE