mktime() not setting proper date/time

bunner_bob

This is driving me crazy - can't figure out what's going on.

mktime() is giving me different times when run from different servers. Of course this would be normal if I were running the function empty, but here's what I'm doing:

$y = date('Y', (mktime() - 10800)); // 3 hour diff w/ server
$m = date('m', (mktime() - 10800));
$d = date('d', (mktime() - 10800));

$this->today = mktime(0,0,0,$m,$d,$y);

(the 3-hour adjust is only because the client's timezone is 3 hours off from the server's - it's done so that the entries they make flip over to the next day at midnight in their time zone, not the server's)

Anyway, $this->today should always be midnight on the day specified, since I'm feeding it zero minutes, seconds, hours and a specific day, month, year. Instead it's 4 hours later in the server's timezone (1122696000) and 7 hours later in the client's timezone (1122706800). So not only is it wrong, it appears to be deriving its hour setting from the server, rather than using the 0 I'm feeding it.

What the heck am I doing wrong? How can I get the zero hour/minute/second of the specified day as a unix timestamp?

Thanks,
Bob

drew010

$this->today = strtotime('-3 hours', mktime(0, 0, 0));

easier and works properly.

bunner_bob

Nope - didn't do it. It DID change both times by 3 hours, but now on the "public" site (where the server is 3 hours off) I'm getting 1122685200 (which divided by 86400 leaves a remainder that's the equivalent of one hour), and on the "local" (development) site I'm getting 1122696000 (which divided by 86400 leaves the equivalent of four hours).

I really need to get the unix equivalent of midnight on the current day. The number generated should be the same regardless of the location of the server or any other settings, unless the server is in the next/previous day (after any adjustments) in which case it should give midnight of the next/previous day. I'm assuming a given unix timestamp means "midnight July 30, 2005" regardless of what timezone the server is in.

My system stores dates in unix formats, and the system relies on a baseline of midnight for determining a day. It looks for database entries with a date = $this->today (for today's entries), date = $this->today + 86400 for tomorrow's entries, and so on. If a date is off by a second, it will effectively "disappear". I'm finding as I move data from one server to the other, areas that appear populated one one are coming up empty on the other because the database dates are 3 hours off from what the script is looking for.

Hopefully that explains what I'm trying to do.

drew010

well what about

strtotime('GMT', mktime(0,0,0));

replace GMT with the timezone you want midnight for.

bunner_bob

Ahh - that's it.

Didn't know it cared about timezones. I would think you'd have to adjust for those explicitly.

Thanks

drew010

well all the time functions by default use the systems timezone. so if you do
echo time();
one a server in california and in new york at the same time (assuming both clocks are set to their locations) you will see two different timestamps.

bunner_bob

What about using gmmktime(0, 0, 0, $month, $day, $year)?

I've got a number of cases in which I need to specify midnight on a specific (calculated) day, rather than just today. Up till now I've been using mktime(0, 0, 0, $month, $day, $year) - if I can just switch those to gmmktime() the modification will be much easier.

I've tried it and it seems to work. Is this a wise option?

drew010

yes that will get you a timestamp in the gmt time zone, which is useful if thats what you need. otherwise you may still need to convert that time back to your local timezone (not too hard but you may need to consider dst). strtotime is very useful for modifying timestamps because of all the different ways there are to change a timestamp.