- substr: documentation ( source)
- str_shuffle: documentation ( source)
- array_merge: documentation ( source)
- join: documentation ( source)
<?php
$r='range';echo substr(str_shuffle(join(call_user_func_array('array_merge',[$r('a','z'),$r(0,9),$r('A','Z'),['`~!@#$%^&*()_+-={}|[]\\:";\'<>?,./']]))),0,15);