Convert DateInterval object to seconds in php

Question

$datetime1 = date_create(\'2009-10-11\');
$datetime2 = date_create(\'2009-10-13\');
$interval = date_diff($datetime1, $datetime2);

How do i convert the

Answer 1

I would only add to shiplu's answer:

function dateIntervalToSeconds($interval)
{
    $seconds = $interval->days*86400 + $interval->h*3600 
       + $interval->i*60 + $interval->s;
    return $interval->invert == 1 ? $seconds*(-1) : $seconds;
}

To handle negative intervals.

Note that - contrary to Brilliand's answer - The code above will consider correctly years, months and dates. Because $interval->days is an absolute value ($interval->d is relative to the month).

EDIT: this function is still not correct, as pointed out by @Brilliand. A counter-example is

new DateInterval('P4M3DT2H'); 

It doesn't handle months well.