//utf8中文字串截取
function csubstr($str,$start,$len){

		preg_match_all("/[
-]|[�-�][�-�]|�[�-�][�-�]|[�-�][�-�][�-�]|�[�-�][�-�][�-�]|[�-�][�-�][�-�][�-�]/", $str, $ar);
		$x=1;
		for($i=0;$i$len){
				break;
			}
			if(ord($ar[0][$i])<128){
				if($x==2){
					$len=$len+1;
					$x=0;
				}
				$x++;
			}

		}

		return join("",array_slice($ar[0],$start,$len));
}