dividing one DateInterval by another

Question

Suppose I have one DateInterval that is 1 year, and another that is 3 months.

Is it possible to divide one by the other and get an answer of 4, that is, there are 4 intervals of 3 months in an interval of 1 year?

Question: what would you expect `1 month divided by 7 days` to return? — Niet the Dark Absol, Dec 01 '17 at 13:56
There might be a way to get this done. Can you post 2 or 3 examples of what you want to achieve? Example: var $datainterval = 4; $month = 3 outcome = 4. — Carlos R, Dec 01 '17 at 13:57

score 0 · Answer 1 · answered Dec 01 '17 at 14:03

You could just try converting your DateIntervals to seconds and dividing that:

$dateInterval1     = new DateInterval('P1Y');
$dateInterval2     = new DateInterval('P3M');
$dateInterval1Secs = date_create('@0')->add($dateInterval1)->getTimestamp();
$dateInterval2Secs = date_create('@0')->add($dateInterval2)->getTimestamp();

var_dump($dateInterval1Secs / $dateInterval2Secs);

Of course, this is really precise, and this code outputs 4.0555555555556

Converting to seconds from Convert DateInterval object to seconds in php

score 0 · Answer 2 · answered Dec 01 '17 at 14:15

Directly no, since DateInterval is an object. Something like this could help based on this answer

$y = new DateTime('@0');
$x = new DateTime('@0');
$secondsOfYear = $y->add(new DateInterval('P1Y'))->getTimestamp();
$secondsOfThreeMonths = $x->add(new DateInterval('P3M'))->getTimestamp();

print_r([$secondsOfYear,$secondsOfThreeMonths,(int)($secondsOfYear/$secondsOfThreeMonths)]);
// output
Array
(
    [0] => 31536000
    [1] => 7776000
    [2] => 4
)

Check it out on PHP Sandbox

score -1 · Answer 3 · answered Dec 01 '17 at 14:00

Dates do not lend themselves easily to mathematical operations. We can just about do addition and subtraction, that's about it. Multiplication makes little sense (1 month times 12 months = 1 square-year?) but division can be understood as "how many of this interval are there?" which can be implemented by repeated subtraction.

Create a DateTimeImmutable for now. add the first of the intervals you are trying to perform division on. Then, subtract the second interval until you obtain a new date/time that is less than (or equal to) your original DateTimeImmutable. Count how many times this takes. That's your division answer.

dividing one DateInterval by another

3 Answers3