Calculating the difference between two dates

[exhaler]

hi all,

 

i'm trying to calculate the time difference between two dates in hours, for example: 2010-12-13 15:26:56 and 2011-12-13 15:26:56

i tried mktime but wasn't able to get a working function.

 

Thanks for the help

[AyKay47]

http://www.php.net/manual/en/datetime.diff.php

might be viable here

[cssfreakie]

or just do:

<?php
$time1 = strtotime('2010-12-13 15:26:56');
$time2 = strtotime('2011-12-13 15:26:56');

echo $result = ($time2 - $time1)/3600; //60seconds * 60min ?> 

[xyph]

These look like timestamps returned from a MySQL database? If so, do it in SQL, it's quite a bit faster.

 

Generally, the best way to do this is to get the UNIX_TIMESTAMP of each date so you can get the difference in seconds, then use simple arithmetic to determine if you want to show how many hours/days/etc difference there is.

 

SELECT UNIX_TIMESTAMP(`date1`) as `date1_stamp`, UNIX_TIMESTAMP(`date2`) as `date2_stamp` FROM `table`

[requinix]

Keep in mind the difference will be actual elapsed time, not what it "looks" like: the difference between 2011-03-13 12am and 2011-03-14 12am is 23 hours.

[AbraCadaver]

And if the dates cross one of the changes for daylight savings time, then you are off by 1 hour one way or the other.  If using calculations then make sure that the timestamp is derived by the date at UTC or GMT or any timezone that doesn't observe daylight savings time.

[xyph]

It depends if you want actual hours passed, or hours passed on a clock/calendar. It's good to point out that potential quirk though.