php截取汉字类

<?
//utf-8格式的
function smarty_modifier_truncate_utf8($string, $length, $etc = '...')
{
    $result = '';
    $string = html_entity_decode(trim(strip_tags($string)), ENT_QUOTES, 'UTF-8');
    $strlen = strlen($string);
    for($i = 0; (($i < $strlen) && ($length > 0)); $i++)
    {
     if($number = strpos(str_pad(decbin(ord(substr($string, $i, 1))), 8, '0', STR_PAD_LEFT), '0'))
        {
            if($length < 1.0)
            {
                break;
            }
            $result .= substr($string, $i, $number);
            $length -= 1.0;
            $i += $number - 1;
        }
        else
        {
            $result .= substr($string, $i, 1);
            $length -= 0.5;
        }
    }
    $result = htmlspecialchars($result, ENT_QUOTES, 'UTF-8');
    if($i < $strlen)
    {
        $result .= $etc;
    }