Difference between DateTimes

[mongoose00318]

I'm trying to subtract get the total number of days between two dates. I have been trying the DateTime date_diff method and the strtotime methods. I have it working mostly; but I have a problem with if the value should be negative. I've tried the invert() on the value that comes back from the date_diff() function but get errors. To sum up what I'm trying to do is:

if ( $diff === 0 ) 
  echo "Today"
elseif ($diff > 0)
  echo "+" . $diff . "Days";
else 
  echo "LATE -" . $diff . "Days";

Something like that. Here is my code...

		//retrieve expected complete time
		if ( isset( $stat[ 'expected_complete_time' ] ) ) {
			$today = new DateTime("now");
			$expected_complete_time = new DateTime($stat[ 'expected_complete_time' ]);
			$today->setTime(12, 0, 0);
			$expected_complete_time->setTime(12, 0, 0);
			
			//calculate difference
			$eta = date_diff($expected_complete_time, $today)->format("%d");;
			
			//future
			if ($today > $expected_complete_time) {
				$eta = '+' . $eta;
			//today
			} elseif ($eta === '0') {
				$eta = 'Today';
			//overdue
			} else {
				$eta = 'LATE:-' . $eta;
			}

		} else 
			$eta = '';

 

[mongoose00318]

No matter the method I use I get positive dates when they should be negative? Here's changes to my code and the results...

$today = new DateTime("now");
$expected_complete_time = new DateTime($stat[ 'expected_complete_time' ]);
$eta = $expected_complete_time->diff($today);
			
$str_eta = $eta->format('%R%d');
echo ': Now: ' . $today->format('d/m/Y') . ': Expected: ' . $expected_complete_time->format('d/m/Y') . ' Diff: ' . $str_eta;

Now: 01/05/2020: Expected: 22/04/2020 Diff: +9 
Now: 01/05/2020: Expected: 01/05/2020 Diff: +0 
Now: 01/05/2020: Expected: 01/05/2020 Diff: +0 
Now: 01/05/2020: Expected: 22/04/2020 Diff: +9 
Now: 01/05/2020: Expected: 23/04/2020 Diff: +8 
Now: 01/05/2020: Expected: 04/05/2020 Diff: -2

[requinix]

8 minutes ago, mongoose00318 said:

Now: 01/05/2020: Expected: 22/04/2020 Diff: +9 
Now: 01/05/2020: Expected: 01/05/2020 Diff: +0 
Now: 01/05/2020: Expected: 01/05/2020 Diff: +0 
Now: 01/05/2020: Expected: 22/04/2020 Diff: +9 
Now: 01/05/2020: Expected: 23/04/2020 Diff: +8 
Now: 01/05/2020: Expected: 04/05/2020 Diff: -2

Looks right to me. What do you think those should be?

[mongoose00318]

I was trying to get something like:

Now: 01/05/2020: Expected: 22/04/2020 Diff: -9 
Now: 01/05/2020: Expected: 01/05/2020 Diff: 0 
Now: 01/05/2020: Expected: 01/05/2020 Diff: 0 
Now: 01/05/2020: Expected: 22/04/2020 Diff: -9 
Now: 01/05/2020: Expected: 23/04/2020 Diff: -8 
Now: 01/05/2020: Expected: 04/05/2020 Diff: +2 (but shouldn't this actually be +3?)

Basically user says the amount of days it takes to complete some work and if today's date  is passed that day then it shows a negative value.

Edited May 1, 2020 by mongoose00318

[requinix]

Oh. Well that's easy:

You simply have the diff backwards. $object->diff($date) is the diff from $object to $date, and works like $date minus $object. $today->diff($tomorrow) is positive, $today->diff($yesterday) is negative.

[mongoose00318]

Oops..yea that fixed it. But. I'm getting - and + on 0 values...? Can I just tell it not to do anything for a 0?

https://imgur.com/a/Vn9RmFl

Also, on this date...

Now: 01/05/2020: Expected: 04/05/2020 Diff: +2 

Shouldn't that say 3 days?

[mongoose00318]

Also, it must be rounding or something? If I set the date for tomorrow; the difference I get is 0. If I put the expected date 2 days out; I get back a difference of 1. Maybe it's using the time in combination with date and not getting a whole day for the difference because of that? The date in the database doesn't have a time. It's just the date.

Edited May 1, 2020 by mongoose00318

[mongoose00318]

What do you think about this?

$today = new DateTime("now");
$expected_complete_time = new DateTime($stat[ 'expected_complete_time' ]);
$eta = $today->diff($expected_complete_time);
			
$str_eta = $eta->format('%r%d');

if($expected_complete_time->format('d/m/Y') === $today->format('d/m/Y')) {
	$eta = 'Today';
} else {
	$eta = ($str_eta+1 == 1) ? $str_eta+1 . ' day' : $str_eta+1 . ' days';
}

https://imgur.com/HTiuvrF

Seems to be doing what I need.

[requinix]

57 minutes ago, mongoose00318 said:

Oops..yea that fixed it. But. I'm getting - and + on 0 values...? Can I just tell it not to do anything for a 0?

Write your own code to format the string according to the diff and invert.

57 minutes ago, mongoose00318 said:

Shouldn't that say 3 days?

Not if it there was a fractional part of a day involved. It's not 2 days, it's 2-point-something days.

56 minutes ago, mongoose00318 said:

The date in the database doesn't have a time. It's just the date.

PHP does not have a "just the date" type. There's always a time value...

34 minutes ago, mongoose00318 said:

What do you think about this?

It's still not quite right. Check the docs for DateInterval and format to make sure you're using them correctly.

[Barand]

1 hour ago, mongoose00318 said:

Also, on this date...

Now: 01/05/2020: Expected: 04/05/2020 Diff: +2 

Shouldn't that say 3 days?

Yes

$a = new DateTime('2020-05-01');
$b = new DateTime('2020-05-04');

echo $a->diff($b)->days;                //-> 3