<?php
$result = "°Freenew°\x90ɮ\xc2\xe4dfg\xa0";
//$result = trim($result,"\xc2"/*"\xa0"*/);
//echo preg_replace('#[\x00-\x1F\x7F-\x9F]#', '', $result);
//reject overly long 2 byte sequences, as well as characters above U+10000 and replace with ?
echo preg_replace('/[\x00-\x08\x10\x0B\x0C\x0E-\x19\x7F]'.
'|[\x00-\x7F][\x80-\xBF]+'.
'|([\xC0\xC1]|[\xF0-\xFF])[\x80-\xBF]*'.
'|[\xC2-\xDF]((?![\x80-\xBF])|[\x80-\xBF]{2,})'.
'|[\xE0-\xEF](([\x80-\xBF](?![\x80-\xBF]))|(?![\x80-\xBF]{2})|[\x80-\xBF]{3,})/S',
'', $result );
/*
//reject overly long 3 byte sequences and UTF-16 surrogates and replace with ?
$some_string = preg_replace('/\xE0[\x80-\x9F][\x80-\xBF]'.
'|\xED[\xA0-\xBF][\x80-\xBF]/S','?', $some_string );
*/
preferences:
38.89 ms | 402 KiB | 5 Q