How to get difference of two dates in php and add that difference to third date to obtain another new date?

Question

There are two variables,

$old_start = new DateTime("2020-12-13 14:20");
$old_end = new DateTime("2021-03-25 12:29");

Now take difference of those two dates:

$gap = $old_end->diff($old_start);

Consider third variable:

$new_start = new DateTime("2020-12-27 11:47");

and based upon this $new_start and $gap, I want a new variable $new_end that is something like add some time period in new starting date to obtain new ending date.

Answer 1

You can achieve that as following, you can learn more about the datetime manipulation from this How we can add two date intervals in PHP

$old_start = new DateTime("2020-12-13 14:20");
$old_end = new DateTime("2021-03-25 12:29");

$interval_diff = $old_start->diff($old_end);

$new_start = new DateTime("2020-12-27 11:47");

$new_end = $new_start->add($interval_diff);

print_r($interval_diff);
print_r($new_end);