- array_map: documentation ( source)
- max: documentation ( source)
- str_split: documentation ( source)
<?php
$msg = "Ce SMS est envoyé depuis SMS Coaching, w 3aywsalk m3a dik 16:20 w mli t9rah 9ola nwa7d siyed issmo Otmane bax y3raf hhhh :-D";
$res = max(array_map('ord', str_split($message)));
echo $res;