Add 13 hours to a timestamp

Question

I have a table with timestamp values like:

    2009-07-14 02:00:00

I need to display them at run time with 13 hours added, like:

    2009-07-14 15:00:00

What's the simplest way to do this in PHP?

Answer 1

you could use http://de3.php.net/manual/en/function.strptime.php to convert it to a unix timestamp. Then you could easily add 13*60*60 to that and use http://de3.php.net/manual/en/function.date.php to convert it back to a timestamp as you like.

anotehr way would be via the explode function, but i think this might be more complicated because you have to look if days/month/years change and stuff

Answer 2

Here's something that you can refer from: http://www.daniweb.com/forums/thread85726.html

Answer 3

Can you do the add as it comes out of the database?

SELECT ... DateAdd(hh, 13, DateField) AS DateField

(SQL Server)

Answer 4

I know that

date( "Y-M-d H:i:s", strtotime( $timestamp_from_array ) + 13 * 3600 );

is smelly, but it will give you an idea.

strtotime converts the timestamp string to a timestamp value, then we add the hours and convert it back to the timestamp format in the array with the date function.

But I suppose what you really want is to use time zones.

Edit: igstan is correct, you should also mind the daylight saving time changes between those offsets.

Answer 5

There are lots of problems with Time Zones and Daylight Saving Time when using basic arithmetic for time calculations. The best solution is to rely on PHP's own date/time functions, like strtotime() or mktime(). I've wrote about DST problems on my blog.

echo date('Y-M-d H:i:s', strtotime('2009-07-14 02:00:00 + 13 hours'));

Answer 6

You have a table with the timestamps? If it's a MySQL database, you could just do this in the database using addtime: SELECT ADDTIME('2007-12-31 23:59:59.999999', '1 1:1:1.000002');

If you are using the PHP Zend Framework, you could do something like:

 $date=new Zend_Date(Array('year'=>$iYear,'month'=>$iMonth,'day'=>$iDay));
 // changes $date by adding 12 hours
 $date->add('12:00:00', Zend_Date::TIMES);

Alternatively, you could do it using native PHP4 functions such as: [faster, less accurate: doesn't account for leap seconds/time zone changes etc]

$datestamp=strtotime('2009-07-14 02:00:00'); // It'll probably be better using mktime
$datestamp=$datestamp+(60*60*13); // 60 seconds times 60 minutes times 13 hours

or [slower, more accurate]

  $datestamp = strtotime('2009-07-14 02:00:00'); // It'll probably be better using mktime
  $newDate = date('Y-m-d H:i:S', mktime(date('H',$datestamp)+13, date('i',$datestamp), date('s',$datestamp), date('m',$datestamp), date('d',$datestamp), date('Y',$datestamp)));

or, if you are using PHP 5 using the Datetime functions

$date = new DateTime('2009-07-14 02:00:00');
date_add($date, new DateInterval("P13H"));

Answer 7

<?php
echo date('Y-m-d H:i:s', strtotime('+13 hours', strtotime('2009-07-14 02:00:00')));
?>