<?php
$a = [3,15,21,32,65];
for ($i = 0; $i < count($a) ; $i++) {
for ($j = $i+1; $j < count($a); $j++) {
if ($a[$i] > $a[$j]) {
$b = $a[$i];
$a[$i] = $a[$j];
$a[$j] = $b;
}
}
}
print_r($a);