How can I change timezones in a php date? - php

I have a date stored in a database in this format:
2011-02-23 13:00:00
I need to return it in ISO8601 format, but it needs to be set to a specific time zone (which is not necessarily the time zone of the server.) What I want to return is this:
2011-02-23T13:00:00-0600
Using this code:
echo date(DATE_ISO8601, strtotime("2011-02-23 13:00:00"));
I get this:
2011-02-23T13:00:00+0000
Is there any way to reset the time zone in the date or strtotime function, or do I need to strip off the 5 rightmost characters and concatenate the desired timezone stamp to the remaining date/time?
EDITED TO ADD:
Although I did accept the solution below of using new DateTime and setting new DateTimeZone, I found an easier way if you don't need to keep resetting the time zone:
date_default_timezone_set('America/Chicago');
$startTime = date(DATE_ISO8601, strtotime("2011-02-23 13:00:00"));

You could use the DateTime class. Datetime objects can be initialized with a specific time zone, and easily transposed to others.
Modified from the manual:
$date = new DateTime('2011-02-23 13:00:00', new DateTimeZone('Pacific/Nauru'));
echo $date->format('c') . "\n";
$date->setTimezone( new DateTimeZone('Europe/Berlin'));
echo $date->format('c') . "\n";

Related

Changing PHP default timezone not working

I am trying to have a line of code added to an html document that is preceded by the time. I want the time zone to be relative to me, however I cannot change it from the default UTC. I have changed in the php.ini file to PST as well as using date_default_timezone_set('America/Los_Angeles'); and yet it still prints the time 7 hours ahead of my timezone. Heres the code that deals with the time:
session_start();
if(isset($_SESSION['name']))
{
date_default_timezone_set('America/Los_Angeles');
$msg = $_POST['text'];
$fo = fopen("log.html", 'a');
fwrite($fo, "<div class=msgln>(".date("g:i A").") <b style=color:red;>".$_SESSION['name']."</b>: ".stripslashes(htmlspecialchars($msg))."<br></div>
");
fclose($fo);
}
Servers should be set to UTC, and you should not be looking to change the default. Instead, what you want to do is create a DateTime object based on the time, then convert it to the timezone you want, and display.
$now = new DateTime();
$now->setTimezone(new DateTimeZone('America/Los_Angeles'));
echo $now->format('g:i A');
I don't know if your format string is valid or not, but the format method is suppossed to be compatible with that accepted by the date() function you were using in your original example.
First make sure you're using a valued timezone. You can find a list of supported timezones in the PHP docs.
The second problem is using date() without specifying the timestamp. This defaults to the timestamp produced by time() which (based on a comment in the documentation) is UTC time. You'll either have to use strftime() or manually subtract the difference from UTC.
If you use 'etc/GMT' you can set the dateTime object to the desired time zone like so:
$dtz = new DateTimeZone('etc/GMT-10');
$dt = new DateTime(date("Y-m-d h:i A"), $dtz);
$date = gmdate("Y-m-d h:i A", $dt->format('U'));

convert to UTC without changing php timezone settings

How can I convert the time zone of a date string in php without changing the default time zone. I want to convert it locally to display only. The php time zone settting should not be modified.
EDIT:
My source time is a UTC string, I want to convert it to a different format, retaining the time zone as UTC, but php is converting it to local timezone.
The code I used was:
date('Y-m-d H:i::s',strtotime($time_str));
How do I retain timezone?
$src_tz = new DateTimeZone('America/Chicago');
$dest_tz = new DateTimeZone('America/New_York');
$dt = new DateTime("2000-01-01 12:00:00", $src_tz);
$dt->setTimeZone($dest_tz);
echo $dt->format('Y-m-d H:i:s');
Note that if the source time is UTC, you can change the one line to this:
$dt = new DateTime("2000-01-01 12:00:00 UTC");
Edit: Looks like you want to go to UTC. In that case, just use "UTC" as the parameter to the $dest_tz constructor, and use the original block of code. (And of course, you can omit the $src_tz parameter if it is the same as the default time zone.)

PHP timezone function not working

I'm creating a forum, which also stores the time a post was sent, and I need to convert that into the user's timezone.
Now, the MySQL DataBase stores the time with UTC_TIMESTAMP() (in a column with the DATETIME type), and I created a little function from the code on http://www.ultramegatech.com/blog/2009/04/working-with-time-zones-in-php/ to convert the time to the user's timezone. This is the function:
function convertTZ($timestamp, $tz='UTC', $format='d-m-Y H:i:s') {
// timestamp to convert
$timestamp = strtotime($timestamp);
// the time formatting to use
$format = $format;
// the time zone provided
$tz = $tz;
// create the DateTimeZone object for later
$dtzone = new DateTimeZone($tz);
// first convert the timestamp into an RFC 2822 formatted date
$time = date('r', $timestamp);
// now create the DateTime object for this time
$dtime = new DateTime($time);
// convert this to the user's timezone using the DateTimeZone object
$dtime->setTimeZone($dtzone);
// print the time using your preferred format
$time = $dtime->format($format);
return $time;
}
And I made a test page at http://assets.momo40k.ch/timezones.php.
Now, when I insert a post into the DataBase at, say, 11:50 in my timezone (which is Europe/Rome), it inserts 09:50 in UTC, wich is correct, according to some online timezone converters.
But when I try to convert it back to Europe/Rome with the convertTZ() function, it returns 09:50, as if Europe/Rome is UTC. If I try converting it to a GMT+2:00 timezone, it returns 10:50. Can anyone fugure out why this is?
P.S: I'm not using the CONVERT_TZ() SQL function because my server does not support named timezones, so this function is my workaround.
Make sure your stored timestamps are UTC:
$date = new DateTime($timestamp, new DateTimeZone("UTC"));
$date->format(DATE_W3C); // does it gives the expected result ?
BTW your function can be simplified to this:
function convertTZ($timestamp, $tz='UTC', $format='d-m-Y H:i:s') {
$dtime = new DateTime($timestamp, new DateTimeZone("UTC"))
$dtime->setTimezone(new DateTimeZone("UTC"));
return $dtime->format($format);
}
MySQL always stores TIMESTAMP fields in UTC internally (that's the definition of a unix timestamp, in fact). So when you SELECT or UPDATE/INSERT/REPLACE, the time you get or set is always in the MySQL server's local time zone.
So a common mistake is to store UTC_TIMESTAMP(), which MySQL interprets as a local time and so the current time gets double-converted to UTC when it stores it internally in the field as a unix TIMESTAMP.

UTC datetime conversion

The values that I received from my device are: 090211 = ddmmyy and 062123 = hhmmss in UTC.
But I found that the time is always 8 hours later if compared to the time that I need. It is because the time for Malaysia is +8:00. First I would like to add 8 hour, and finally I would like to store this kind of date format into my MySQL database as "2011-02-09 06:21:23". How would I convert these values?
To convert in PHP to a datetime, you will need the function DateTime::createFromFormat(); This function will return a DateTime.
Using this function you can also pass the timezone as a parameter.
Example:
$date = DateTime::createFromFormat( 'dmy Gms', '090211 062123', new DateTimeZone("Europe/Amsterdam") );
You can create a output a following:
echo $date->format('Y-m-d H:i:s');
or UNIX timestamp for the MySQL:
echo $date->format('U');
Hope this helps!
PHP has both localtime and gettimeofday functions, are you by chance using the wrong one (or misinterpreting its results)?

PHP DateTime Inconsistency? What am I missing?

Using PHP 5.2.5 I was working with some DateTime objects and noticed a time that seemed off. The problem I'm having may be related to timezones, but I'm not sure - I'm creating a DateTime from a Unix Time Stamp and getting different/unexpected results depending on how I output it.
I created the following to easily illustrate the "issue":
$timezone = new DateTimeZone('America/Chicago');
$now = time();
$now_datetime = new DateTime('#' . $now, $timezone);
echo phpversion() . "\n\n";
echo $now . "\n";
echo $now_datetime->format('U') . "\n\n";
echo date('g:i:sa', $now) . "\n";
echo $now_datetime->format('g:i:sa') . "\n\n";
This outputs the following:
5.2.5
1287676530
1287676530
10:55:30am
3:55:30pm
I'm currently in the correct timezone, and the server shows the "right" time (10am) when using the date() function to output a formatted date, as well as 'America/Chicago' being the default timezone on that machine. But, when outputting values via DateTime::format(), the times are very different.
I added the ->format('U') just to verify that it was holding the correct timestamp.
So, I'm probably doing something wrong or I have the wrong expectations. So what am I missing?
It seems like a timezone issue with DateTime, but if that's the case, why does it show "now" in America/Chicago as ... wrong?
The timezone you 'insert' into DateTime is the timezone of the string, which may not be your current timezone, so PHP can calculate the actual datetime, not the timezone it uses to format your output. If you want it to output the time in a specific timezone, use $now_datetime->setTimezone($timezone).
The manual on DateTime's constructor has the answer:
The $timezone parameter and the current timezone are ignored when the $time parameter either is a UNIX timestamp (e.g. #946684800) or specifies a timezone (e.g. 2010-01-28T15:00:00+02:00).
This means that your timestamp is treated as a GMT one, explaining the 7 hours' difference.

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