php - DateTime 类如何处理负日期间隔

Question

我有一个简单的函数，它使用 DateTime diff 函数返回两个日期之间的天数。但是现在如果结束日期早于开始日期，它仍然返回一个正数。有没有办法使用这种方法返回负差？还是我打赌最好先在我的函数中检查 strtotime ？理想情况下，我认为我只会返回 0 的负差。

//Returns the total number of days between two dates
function count_days($start_date, $end_date){

    $d1 = new DateTime($start_date);
    $d2 = new DateTime($end_date);
    $difference = $d1->diff($d2);
    return $difference->days;

}

Answer 1

使用r标志在其中获取负号：

function count_days($start_date, $end_date){

    $d1 = new DateTime($start_date);
    $d2 = new DateTime($end_date);
    $difference = $d1->diff($d2);
    return $difference->format('%r%a days');

}

Answer 2

检查 $difference->invert

function count_days($start_date, $end_date){

   $d1 = new DateTime($start_date);
   $d2 = new DateTime($end_date);
   $difference = $d1->diff($d2);
   if ($difference->invert == 1) { //if 1 then difference will in minus other wise inplus
      return -$difference->d;
   } else {
     return $difference->d;
   }

}