php字符串截取，支持中文和其他编码

/**
 * 字符串截取，支持中文和其他编码
 * static
 * access public
 * @param string $str 需要转换的字符串
 * @param string $start 开始位置
 * @param string $length 截取长度
 * @param string $charset 编码格式
 * @param string $suffix 截断显示字符
 * return string
 */

function msubstr($str, $startto, $leng, $charset = "utf-8", $suffix = true)
{
    if ($startto) {
        $start = $startto;
    } else {
        $start = 0;
    }
    $length=$leng?:5;
    if (mb_strlen($str, $charset) > $length) {
        if (function_exists("mb_substr")) {
            if ($suffix)
                return mb_substr($str, $start, $length, $charset) . "...";
            else
                return mb_substr($str, $start, $length, $charset);
        } elseif (function_exists('iconv_substr')) {
            if ($suffix)
                return iconv_substr($str, $start, $length, $charset) . "...";
            else
                return iconv_substr($str, $start, $length, $charset);
        } else {
            $re['utf-8'] = "/[\x01-\x7f]|[\xc2-\xdf][\x80-\xbf]|[\xe0-\xef][\x80-\xbf]{2}|[\xf0-\xff][\x80-\xbf]{3}/";
            $re['gb2312'] = "/[\x01-\x7f]|[\xb0-\xf7][\xa0-\xfe]/";
            $re['gbk'] = "/[\x01-\x7f]|[\x81-\xfe][\x40-\xfe]/";
            $re['big5'] = "/[\x01-\x7f]|[\x81-\xfe]([\x40-\x7e]|\xa1-\xfe])/";
            preg_match_all($re[$charset], $str, $match);
            $slice = join("", array_slice($match[0], $start, $length));
        }
        return $suffix ? $slice . '...' : $slice;
    } else {
        return $str;
    }
}