php字符串转数组，支持中文

/**
 * 把字符串转成数组，支持汉字，只能是utf-8格式的
 * @param $str
 * @return array
 */
function StringToArray($str)
{
    $result = array();
    $len = strlen($str);
    $i = 0;
    while($i < $len){
        $chr = ord($str[$i]);
        if($chr == 9 || $chr == 10 || (32 <= $chr && $chr <= 126)) {
            $result[] = substr($str,$i,1);
            $i +=1;
        }elseif(192 <= $chr && $chr <= 223){
            $result[] = substr($str,$i,2);
            $i +=2;
        }elseif(224 <= $chr && $chr <= 239){
            $result[] = substr($str,$i,3);
            $i +=3;
        }elseif(240 <= $chr && $chr <= 247){
            $result[] = substr($str,$i,4);
            $i +=4;
        }elseif(248 <= $chr && $chr <= 251){
            $result[] = substr($str,$i,5);
            $i +=5;
        }elseif(252 <= $chr && $chr <= 253){
            $result[] = substr($str,$i,6);
            $i +=6;
        }
    }
    return $result;
}