如何在PHP中获得负值的日期差异

Question

I'm trying to get the date difference in minus value if the start_Date is greater than the end_date. below is my code

    $diff =  strtotime('2019-07-31') - strtotime('2019-07-21');
    $date_diff = round($diff / 86400);

the code gives me 10 as answer, but i want -10 . how should i get it?

Answer 1

All you need to use %r format. This format prints a minus (-) sign if the difference is negative, or nothing otherwise.

<?php

function dateDifference($date_1 , $date_2 , $differenceFormat = '%r%a' ) {
    $datetime1 = date_create($date_1);
    $datetime2 = date_create($date_2);

    $interval = date_diff($datetime1, $datetime2);

    return $interval->format($differenceFormat);

}

echo dateDifference('2019-07-31', '2019-07-21'); // -10

Answer 2

Here it is. just put a negative sign before rounding.

$diff =  strtotime('2019-07-31') - strtotime('2019-07-21');
$date_diff =  - round($diff / 86400); // here is the change you need

echo $date_diff;

Output:

-10