get time between times in HH:MM:SS format - php

Question

I have looked everywhere for a simple answer to this but I have not been able to find a solution that either works or meets my requirements.
I am looping through data, that looks similar to this:
Array
(
[0] => 4c36fd909b37208b
[1] => event:
[2] => start_scan
[3] => 2012-08-17 12:01:15
)
Array
(
[0] => 4c36fd909b37208b
[1] => sysaction:
[2] => lower_device
[3] => 2012-08-17 12:01:19
)
Array
(
[0] => 4c36fd909b37208b
[1] => event:
[2] => how_to_use_displayed
[3] => 2012-08-17 12:01:46
)
Array
(
[0] => 4c36fd909b37208b
[1] => event:
[2] => scan_displayed
[3] => 2012-08-17 12:01:59
)
Array
(
[0] => 4c36fd909b37208b
[1] => sysaction:
[2] => layer_1_display_on_recognition
[3] => 2012-08-17 12:02:23
)
I want to work out the time between two dates and the result needs to be in the format HH:MM:SS.
In the example data above, I need the difference between 2012-08-17 12:01:15 and 2012-08-17 12:02:23, which should be 00:01:08.
I have tried to use the code from here: http://www.if-not-true-then-false.com/2010/php-calculate-real-differences-between-two-dates-or-timestamps/ but it keeps returning 00:00:20
I have also tried this (where the date in the first array is saved as $xpTime and the date in the last array is set to $xpEndTimeTmp):
$start = new DateTime($xpTime);
$end = new DateTime($xpEndTimeTmp);
$diff = $start->diff($end);
$xpDuration = date('H:i:s', strtotime($diff->h.':'.$diff->i.':'.$diff->s));
But that seems to be working either (it returns the same hour, minute and a different second).
I hope someone can help me, tell me what I am doing wrong, or has sample code that could that could set me on the right track!

Answer 1

$t1 = '2012-08-17 12:01:15';
$t2 = '2012-08-17 12:02:23';
echo gmdate("H:i:s", strtotime($t2) - strtotime($t1));
Result
00:01:08

Answer 2

This version also works when the difference is more than 24 hours:
$start = strtotime('2012-08-17 12:01:15');
$end = strtotime('2012-08-17 12:02:23');
$delta = $end - $start;
$hours = floor($delta / 3600);
$remainder = $delta - $hours * 3600;
$formattedDelta = sprintf('%02d', $hours) . gmdate(':i:s', $remainder);
echo $formattedDelta;

Answer 3

If you only want to know how to calculate the time-difference, there is no need to supply all that code in your question.
A simple: 'I need the difference between 2012-08-17 12:01:15 and 2012-08-18 12:02:23, which should be 24:01:08' would have been much clearer. In this case Janis Elsts' answer beat me to it :)
If however you put the example-code there for a reason, because you also want to know how to get the first and last time, you should look into multi-dimensional array's (combined with a working time-difference routine).
So assuming you have stuffed all your single array's in one wrapping array called $log, you would then do something like:
$timeDiff = strtotime(end($log)[3]) - strtotime(reset($log)[3]);
$hours = floor($timeDiff / 3600);
$remainder = $timeDiff - $hours * 3600;
$formattedTime = sprintf('%02d', $hours) . gmdate(':i:s', $remainder);
echo $formattedTime;