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);
?>
