<?php
var_dump(mb_str_split('hello 小姐 韩语中字全集'));
var_dump(utf8_split('hello 小姐 韩语中字全集'));
var_dump(utf8_split_by_mb('hello 小姐 韩语中字全集'));


function utf8_split($str){
	$bin11 = 0xC0;
	$bin10 = 0x80;

	$ch11 = chr($bin11);
	$ch10 = chr($bin10);

	$data = array();

	$str_len = strlen($str); //str length
	$pos = -1; //postion

	for($i=0; $i<$str_len; $i++){
		if(($str{$i} & $ch11) != $ch10){
			++$pos;
		}
		isset($data[$pos]) or $data[$pos] = '';
		$data[$pos] .= $str{$i};
	}

	return $data;
}

function mb_str_split( $string ) {
    # Split at all position not after the start: ^
    # and not before the end: $
    return preg_split('/(?<!^)(?!$)/u', $string );
}

function utf8_split_by_mb($string){
	$stop   = mb_strlen( $string);
	$result = array();

	for( $idx = 0; $idx < $stop; $idx++)
	{
	   $result[] = mb_substr( $string, $idx, 1);
	}

	return $result;
}

?>