isUTF8

isutf8.php

<?php 
public static function isUTF8($string){
		return preg_match('%(?:
		[\xC2-\xDF][\x80-\xBF]        # non-overlong 2-byte
		|\xE0[\xA0-\xBF][\x80-\xBF]               # excluding overlongs
		|[\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}      # straight 3-byte
		|\xED[\x80-\x9F][\x80-\xBF]               # excluding surrogates
		|\xF0[\x90-\xBF][\x80-\xBF]{2}    # planes 1-3
		|[\xF1-\xF3][\x80-\xBF]{3}                  # planes 4-15
		|\xF4[\x80-\x8F][\x80-\xBF]{2}    # plane 16
		)+%xs', $string);
	}