function substr_text($str, $start=0, $length, $charset="utf-8", $suffix=""){

       if(function_exists("mb_substr")){//mb_substr函数不是php内置函数，需要加载php.mbstring.dll才能使用，否则报错

              return mb_substr($str, $start, $length, $charset).$suffix;

       }elseif(function_exists(‘iconv_substr‘)){

              return iconv_substr($str,$start,$length,$charset).$suffix;

       }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 $slice.$suffix;

       }

}

print_r(substr_text(‘字符串截取‘, 1, 3))

【技术宅1】实现中文字串截取无乱码的方法