PHP中截取UTF-8中文字符串

 

/**
 * 
 * @todo 截取中文字符串不乱码
 * @param string $str
 * @param int $start
 * @param int $length
 * @param string $charset
 * @param string $suffix
 */
function msubstr($str, $start=0, $length, $charset="utf-8", $suffix=true) {
     if(function_exists("mb_substr"))
         $slice = mb_substr($str, $start, $length, $charset);
     elseif(function_exists('iconv_substr')) {
         $slice = iconv_substr($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;
 }