php DateTime diff方法行为

Question

I have to find the days until an expiration date. I tried to use diff method of DateTime class.

$dataexp = 2013-11-06 00:00:00 ;
$now = 2013-11-05 13:00:00 ;

$dtn = new DateTime('now');
$dte = new DateTime($dataexp);

$diff = $dtn->diff($dte);

$days = sprintf("%01d", $diff->days);

$days ---> display 1

My problem is if the dataexp is in the past of 1 day the result of diff is 1 and not -1

$dataexp = 2013-11-04 00:00:00 ;
$now = 2013-11-05 13:00:00 ;

$dtn = new DateTime('now');
$dte = new DateTime($dataexp);

$days = sprintf("%01d", $diff->days);

$days ---> display 1

What method could I use to get what I want? (-1 days)? Thanks

Answer 1

See DateInterval::format(), specifically the r format character.

echo $diff->format('%r%d');