Q:

How do I compare two DateTime objects in PHP 5.2.8?

Having a look on the PHP documentation, the following two methods of the DateTime object would both seem to solve my problem:

DateTime::diff : Get the difference and use that to determine which is more ancient.
DateTime::getTimestamp : Get the UNIX timestampt and compare those.

Both these methods are marked in the doco as being available in version >= 5.3 (and, not surprisingly, if I try to call them I find they don't exist). I can't find any specific documentation for 5.2.8 so I am not sure if there are equivalent methods in my version.  I have Googled the problem and found an eclectic range of solutions, none of which answer my very simple requirements:

How do I compare two DateTime objects?
Where can I find the doco for previous PHP versions? Specifically version 5.2.8?

For some context, I have the following code:
$st_dt = new DateTime(verifyParam ('start_date'));
$end_dt = new DateTime(verifyParam ('end_date'));

// is the end date more ancient than the start date?
if ($end_dt < $start_dt) 

Apparently there is no comparison operator on this guy.  
Edit
Apparently my assumptions were completely false (thanks Milen for illustrating this so effectively).  There is a comparison operator and it works just fine thanks.  Sometimes I really miss a compiler.  The bug is in the code above, I am sure you will find it much faster than I did :).

A:

The following seems to confirm that there are comparison operators for the DateTime class:
dev:~# php
<?php
date_default_timezone_set('Europe/London');

$d1 = new DateTime('2008-08-03 14:52:10');
$d2 = new DateTime('2008-01-03 11:11:10');
var_dump($d1 == $d2);
var_dump($d1 > $d2);
var_dump($d1 < $d2);
?>
bool(false)
bool(true)
bool(false)
dev:~# php -v
PHP 5.2.6-1+lenny3 with Suhosin-Patch 0.9.6.2 (cli) (built: Apr 26 2009 20:09:03)
Copyright (c) 1997-2008 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2008 Zend Technologies
dev:~#

A:

From the official documentation:

As of PHP 5.2.2, DateTime objects can be compared using comparison operators.

$date1 = new DateTime("now");
$date2 = new DateTime("tomorrow");

var_dump($date1 == $date2); // false
var_dump($date1 < $date2); // true
var_dump($date1 > $date2); // false

For PHP versions before 5.2.2 (actually for any version), you can use diff.
$datetime1 = new DateTime('2009-10-11'); // 11 October 2013
$datetime2 = new DateTime('2009-10-13'); // 13 October 2013

$interval = $datetime1->diff($datetime2);
echo $interval->format('%R%a days'); // +2 days

A:

You can also compare epoch seconds : 
$d1->format('U') < $d2->format('U')

Source : http://laughingmeme.org/2007/02/27/looking-at-php5s-datetime-and-datetimezone/
(quite interesting article about DateTime)

