an other way to str_split multibyte string:<?php$s='әӘөүҗңһ';$temp_s=mb_convert_encoding($s,'UTF-16','UTF-8');$temp_a=str_split($temp_s,4);$temp_a_len=count($temp_a);for($i=0;$i<$temp_a_len;$i++){ $temp_a[$i]=mb_convert_encoding($temp_a[$i],'UTF-8','UTF-16');}echo('<pre>');print_r($temp_a);echo('</pre>');define('SLS',mb_convert_encoding('/','UTF-16'));$temp_s=mb_convert_encoding($s,'UTF-16','UTF-8');$temp_a=str_split($temp_s,4);$temp_s=implode(SLS,$temp_a);$temp_s=mb_convert_encoding($temp_s,'UTF-8','UTF-16');echo($temp_s);?>