截图多余字符，中英文，避免截取中文乱码

function utf8_strlen($string = null) {
				// 将字符串分解为单元
				preg_match_all('/./us', $string, $match);
				// 返回单元个数
				return count($match[0]);
			}
		   	function sub_content($content, $length){
				$len = utf8_strlen($content);
				for($i = 0 ; $i < $len ; $i++){
					$arr[$i] = mb_substr($content,$i,1,'utf-8');
				}
				$get_length = 0;
				$result = '';
				foreach($arr as $code){
					$result .= $code;
					
					if(strlen($code) > 1){
						$get_length += 2;
					}else{
						$get_length += 1;
					}
					if($get_length >= $length){
						break;
					}
				}
				return $result;
			}
 echo   sub_content($rows["Description"],18);