datetime - PHP: Wrong Time Calculation

235

I am working on a project and writing a function to add two different times. The times are stored in database as a string.

I'm:

Pulling value from db
converting it into time usingstrtotime
adding times usingdate function

Here is my code:

$time_1     = '1:00';
$time_2 = '0:05';

//should be 1:05, whereas it prints 04:05
echo date("H:i", strtotime($time_1) + strtotime($time_2));

Please tell me, what is wrong with above code and how it can be fixed?

Thanks

232

Answer

Solution:

Your problem is because returns the number of seconds since the Unix Epoch (Jan 1 1970). So what you are getting is not values of60 and5, but something more like1537570800 and1537567500. When you add those two values together, you end up with a date far in the future, with what looks effectively like a random time. To compensate for this, you need to subtract the value ofstrtotime at the start of the day to make the second time a relative time e.g.:

echo date("H:i", strtotime($time_1) + strtotime($time_2) - strtotime('00:00'));

Output:

01:05

Update

Since it turns out that the sum of the two times can exceed 24 hours, the above code will not work (the maximum time it will display is23:59 before rolling over to00:00. So it is necessary to convert both times to a relative number of minutes to the start of the day, add them and then display as hours and minutes:

$time_1 = '12:00';
$time_2 = '14:30';
$time_sum = (strtotime($time_1) + strtotime($time_2) - 2 * strtotime('00:00')) / 60;
printf('%02d:%02d', intdiv($time_sum, 60), $time_sum % 60);

Output:

26:30

257

Answer

Solution:

Use DateTime::createFromFormat function, and taking ideas from Adding two DateTime objects in php

$time_1 = '1:00';
$time_2 = '0:05';
$t1 = DateTime::createFromFormat('G:i', $time_1);
$t2 = DateTime::createFromFormat('G:i', $time_2);

$interval1 = $t1->diff(new DateTime('00:00:00')) ;
$interval2 = $t2->diff(new DateTime('00:00:00')) ;

$e = new DateTime('00:00');
$f = clone $e;
$e->add($interval1);
$e->add($interval2);
$total = $f->diff($e)->format("%H:%I:%S");

Additional Details:

G and H 24-hour format of an hour with or without leading zeros
i Minutes with leading zeros 00 to 59

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