finding length of time from two date/time entries

[pedalpete]

I have a bunch of events which I extract from my database, some of these events extend over a night, some take place during a single day.

In the database I have the start/end times of the event, and I am trying to calculate the length of the event.

I've tried a ton of stuff, but I can't seem to get this working properly. If an event lasts from 10pm, Dec 2nd to 5am Dec3, I want it to return 7 hours.

Here's the code as I have it now.

 list($year2, $month2, $day2) = split('[/.-]', $row3['startDate']);
 list($hour2, $min2, $sec2) = split(':', $row3['startTime']);
$startAll = date('H:i:s, d-m-Y', mktime($hour2,$min2,$sec2, $month2, $day2, $year2));
 
 list($year3, $month3, $day3) = split('[/.-]', $row3['endDate']);
 list($hour3, $min3, $sec3) = split(':', $row3['endTime']);
$endAll = date('H:i:s, d-m-Y', mktime($hour3,$min3,$sec3, $month3, $day3, $year3));
 
$length = date('H:i', $endAll-$startAll);
 
echo $length.'<br />'.$startAll.'<br/>'.$endAll;
 

This should be simple, but maybe it isn't
Thanks
Pete

[pedalpete]

I'm answering my own thread here in the hope of helping somebody in the future.

previously I was trying to subtract an entire date/time range and it wasn't working for me.
Instead, I have converted the date/time to seconds and then subtract one from the other, then convert the result to hours. Pretty simple actually.

 list($year2, $month2, $day2) = split('[/.-]', $row3['startDate']);
 list($hour2, $min2, $sec2) = split(':', $row3['startTime']);
$startAll = date('U', mktime($hour2,$min2,$sec2, $month2, $day2, $year2));
 
 list($year3, $month3, $day3) = split('[/.-]', $row3['endDate']);
 list($hour3, $min3, $sec3) = split(':', $row3['endTime']);
$endAll = date('U', mktime($hour3,$min3,$sec3, $month3, $day3, $year3));
 
$length =  ($endAll-$startAll)/(60*60);
 

I hope somebody finds this useful.