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run code in 300+ PHP versions simultaneously
<?php $n = 38; $c = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890-_'; for ($x=0; $x<$n; $x++) { $c = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz01234567890'; if (($x<$n) && ($x > 0) && ($s < 2)) { $c .= '-_'; } $r .= substr($c, mt_rand(0, strlen($c) - 1), 1); if (($r == '_') || ($r == '-')) { $s++; } } echo $r;

preferences:
37.64 ms | 402 KiB | 5 Q