strtotime question

condoug

I need to find out of the difference between two times is greater or less than 30 minutes. So I wrote the following code:

$now = strtotime("17:40:56");
$then = strtotime("17:34:34");

$r = ($now - $then);

echo date('H:i:s',$r);

So, I expected the time to be shown to be 00:06:22 but for some reason it is 01:06:22

Can anyone explain where I am going wrong with this?

Thanks
Doug

CoderDan

you get 2 timestamps, with the result being the number of seconds difference, then you use it as a timestamp, which, based on your time difference, is the hour of that timestamp, back in 1970 or whenever.

you'll need to write a secondsToString() type function that divides by 60 for minutes, and shows teh remainder as seconds. You can also make it calculate hours, days, weeks, etc also. (months would be based on an average month length, same for years)

condoug

Thanks for the reply but that doesn't make sense to me. Surely this method should work??

All I am doing is converting two different times to timestamps, executing an equation between them and turning the result back to a readable time but for some reason it is adding an hour to the time.

Even this adds one hour:

$lasttime 		= strtotime('09:22:56');
$currenttime 	= strtotime('now');

$r = ($currenttime - $lasttime);

echo date('H:i:s',$r);

At the time of execution the resulting time was 01:00:08 when it should have just been 00:00:08.

CoderDan

strtotime() returns a unix timestamp. this is the number of seconds since midnight, january first, 1970.
date() takes a unix timestamp as it's second argument, and outputs it based on your first argument format as time within your system's timezone.

when you subtract one date and time's seconds from another, the esult is the number of seconds difference, and is not a valid unix timestamp.
Thus, using it with date() will not give you the results you expect.

if you want to display the resulting seconds as a amount of time, it is a pretty basic function, and there are plenty of examples out there search google for 'php concert seconds to time'.