Let's say I detect the users timezone offset with:
var tz = (new Date).getTimezoneOffset()/60;
and send the value of -5 to PHP, so:
<?php
date_default_timezone_set('UTC');
$tz = $_POST['tz']; // -5
$date = strtotime('now');
I want to store the timestamp as UTC in the database, but when displayed to the user I want to apply the timezone offset. So assuming $tz is -5 for EST, how can I apply it to the timestamp in order to display a date('M d Y H:i') in my local timezone ?
Bonus question: How can I have it show time for PST only? I assume by finding the PST offset and just specifying a hardcoded PST number to the equation that will be used in the original answer.
Related
This is the coding and it is echoing with the right format but the fact that the date is wrong when it prints out.
Output: 31 Dec 1969 19:33
Database Timestamp 2016-05-20 21:53:17
<?php
date_default_timezone_set('ECT');
$timestamp = 1456778973;
echo date('d M Y H:i',$row['timestamp']);
?>
and i have tried doing the date in different ways and still the same result
In the code sample you posted, $row['timestamp'] has not been set, so the date is constructed with timestamp 0, also known as epoch, or the date that is being echoed.
If you change it as follows, it should work fine:
<?php
date_default_timezone_set('ECT');
$timestamp = 1456778973;
echo date('d M Y H:i', $timestamp); ?>
Side note:
Time zone ECT is not a valid time zone code in PHP. If I assume correctly that you mean european central time, you would have to specify CET instead.
ECT doesn't exist as a valid TimeZone, did you mean CET perhaps?
The correct way to do this is using the DateTime class, i.e.:
$date = new DateTime();
$date->setTimestamp(1456778973);
$tz = new DateTimeZone("America/Denver");
$date->setTimezone($tz);
echo $date->format('d M Y H:i');
PHPFiddle Demo
Note:
Dates should always be stored in DB as UTC (timestamp aka unix time), then you can add or subtract the timezone offset using the DateTime class.
Would you know what the offset would be for mountain standard time?
Mountain Time: America/Denver
Mountain Time (no DST): America/Phoenix
List of Supported Timezones
I know this question has been answered many many times. I came in to a solution to solve this and its goes like this. I store all time stamps for each post in UTC on the server. Now i need to display the time stamp for a given timezone. I do this:
$tz : requested timezone
$ts : timstamp on db
$newts : new timestamp
$datetime = date('m/d/Y g:i a', $ts);
$dt = new DateTime($datetime, new DateTimeZone('UTC'));
date_default_timezone_set(trim($tz));
$newts = $dt->format('U');
date_default_timezone_set('UTC');
However the resulting time stamp is 60~ seconds higher than what is should be.
What am i doing wrong?
You're close, all you need to do is create the original DateTime object based on the timestamp/server timezone then set the new timezone and print the result, like so:
$datetime = new DateTime('#'.$ts, new DateTimeZone('UTC'));
$datetime->setTimezone(new DateTimeZone($tz));
print $datetime->format('m/d/Y g:i a');
The unix timestamp will be the same regardless of the timezone (it is TZ agnostic). The offset occurs when displaying it for different time zones. This is you can test this by printing the unix timestamp for each different timezone (they will be the same).
The U format gives you the number of "seconds since the Unix Epoch (January 1 1970 00:00:00 GMT)". That number does not depend on where on earth you are. So even if it might be 14:59 at your place while it's 10:24 at my place, the number of seconds since January 1 1970 00:00:00 GMT is the same at both our places. A "time stamp for a given timezone" does not make sense.
Given a unix timestamp and timezone offset relative to UTC (e.g. -5), is it possible to calculate if DST is active?
I can do something like:
<?php
echo 'DST enabled? ' . date('I', 1345731453) ."<br>";
?>
But I cannot see how to pass in an offset or a TimeZone.
Im guessing also that there is a difference between the timezone and the offset, given that specific countries support DST?
Appreciate any thoughts.
Correct, you need to start with date and tz to determine offset.
in 5.3+ you can get transitions for start/end period, so you can just use your timestamp for both, something like this:
$inputTime = $your_unix_timestamp;
$inputTZ = new DateTimeZone('Europe/London');
$transitions = $inputTZ->getTransitions($inputTime,$inputTime);
$offset = $transitions[0]['offset'];
$offset is the DST offset at the time in question
Get the timezone with:
$old_zone = ini_get('date.timezone');
Change it to the one you want:
ini_set('date.timezone', 'Europe/Brussels');
Revert back:
ini_set('date.timezone', $old_zone);
The PHP timestamp is always UTC. Depending on your timezone setting it determine what time to show.
How would I take a stored date, like 2011-01-30 18:23:49, and adjust it to any chosen timezone? Is there a simple way such as simply defining the time zone by abbreviation or adding/subtracting x amount of hours?
Basically I want users to be able to choose their time zone and this default date be adjusted to fit theirs.
Have the user choose their time zone
Use that zone name or offset with date_default_timezone_set to set the default time zone used in date functions throughout the rest of script execution.
Use date('Z') to get that time zone's offset from GMT in seconds
Convert your stored date to a timestamp with strtotime -- UNIX timestamps are always GMT, so you now have the time in GMT.
Add the offset from step 3 to convert that time to the user's time zone.
Use date again to format the timestamp as a string in the desired display format.
Example:
$user_timezone = 'America/Los_Angeles';
$stored_time = '2011-01-30 18:23:49';
date_default_timezone_set($user_timezone);
$timestamp = strtotime($stored_time);
$local_timestamp = $timestamp + date('Z');
$local_date = date('Y-m-d H:i:s', $local_timestamp);
echo $local_date;
Here comes my solution. I tested it with America/Los_Angeles as the servers timezone, and my timezone as the users. I assume that the time is stored using the servers timezone.
<?php
// My (user) timezone
$user_timezone = 'Europe/Berlin';
// Server timezone
$stored_timezone = 'America/Los_Angeles';
// Date/Time stored in your DB, using timezone of the server (yours, that is)
$stored_datetime = '2011-01-29 22:40:00'; // this is the current time in L.A.
// Setting default to servers timezone if not done before
date_default_timezone_set($stored_timezone);
// converting to unix timestamp
$stored_timestamp = strtotime($stored_datetime);
// setting default to users timezone
date_default_timezone_set($user_timezone);
// converting to timestamp
$user_datetime = date('Y-m-d H:i:s', $stored_timestamp);
// setting default back to servers timezone
date_default_timezone_set($stored_timezone);
echo $user_datetime; // output is my current time
I've found many examples about UTC tables and php date methods to convert it, but I still miss a simple way after got server date, to converting it into an user timezone selection on my web page.
On this page http://vkham.com/UTC.html I've found a clear guide to understand the range, but I don't know how to connect for example "Europe/Rome" on the table, so there is something more clear about it?
I know the timezone of my server (America/Chicago) but I still don't know a way to change it from UTC method to a different timezone selected from the user machine (for example "Europe/Rome")
I tryied something, but I'still miss something, and i don't know what is it:
<?php
$timezone = date ("e");
$date = date ('Y-m-d H:i:s');
print $date." - this is my server date, and his timezone is - $timezone<br/>";
$user_timezone = "Europe/Rome"; // there is a way to convert Europe/Rome to UTC -13?
$selected_timezone = "-13"; // is -13 like Europe/Rome in all cases or only because my server is America/Chicago?
$date_user = date ("Y-m-d H:i:s $selected_timezone");
$str_date_user = strtotime ($date_user);
$new_user_date = date ('Y-m-d H:i:s', $str_date_user);
print $new_user_date . " - this is my server date, and his timezone is - $user_timezone";
?>
Doesn't exist a way to convert Europe/Rome to -13 for UTC timezone?
Is -13 like Europe/Rome in all cases or only because my server is America/Chicago?
You can use gmdate to generate a date that is displaying the UTC time - whatever timezone your server is running in. Then you can simply add the timezone difference as hours * 3600 to the timestamp you use for generating the date to get the user's time.
A different way would be setting the local time temporary to the user's timezone by using date_default_timezone_set.
A simple example for the first idea would be the following:
<?php
$offset = -13 * 3600; // timezone offset for UTC-13
$utcTime = gmdate( 'd.m.Y H:i' );
$userTime = gmdate( 'd.m.Y H:i', time() + $offset );
?>