php代码
function utf8_substr($str, $from, $len = 180, $suffix = '') {
$str = trim($str);
$str = strip_tags($str);
$pre_len = strlen($str);
$str = preg_replace('#^(?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'. $from .'}'.'((?:[\x00-\x7F]|[\xC0-\xFF][\x80-\xBF]+){0,'. $len .'}).*#s', '$1', $str);
if ($pre_len != strlen($str)) {
$str .= $suffix;
}
return $str;
} 
