<?php
function generateRandomString($length = 22)
{
return substr(str_shuffle(str_repeat($x = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ', ceil($length / strlen($x)))), 1, $length);
}
$generated = [];
for ($i = 0; $i < 10000; $i++) {
$generated[] = generateRandomString();
}
var_dump(count(array_unique($generated)));