<?php
$c = new Collator("en_US"); // should work with any locale
$a = ["02#aa", "02#ab", "03#a", "02#a", "03#x", "03#b", "03#ba", "03#b", "04#a", "03#f"];
echo 'collator sort:' . PHP_EOL;
$c->sort($a, Collator::SORT_STRING); // SORT_REGULAR produces same result
var_dump($a);
echo 'expected results:' . PHP_EOL;
sort($a, SORT_STRING);
var_dump($a);
preferences:
63.57 ms | 402 KiB | 5 Q