how to convert php date formats to GMT and vice versa? - php

Question

i am new to php.
i want to write a function where i need user to input date in any date format including DST,into GMT format and again later back into the original entered format.please any body help me.

Answer 1

Although the gmdate functions are available. If you are using PHP 5.2 or greater, then consider using the DateTime object.
Here's code to switch to GMT
$date = new DateTime();
$date->setTimezone(new DateTimeZone('GMT'));
and back to the default timezone...
$date = new DateTime('2011-01-01', new DateTimeZone('GMT'));
$date->setTimezone(new DateTimeZone(date_default_timezone_get()));
Using the DateTime object lets your create a datetime, just like the procedural functions, except that you keep a reference to an instance.
e.g.
// Get a reference to Christmas of 2011, at lunch time.
$date = new DateTime('2011-12-25 13:00:00');
// Print the date for people to see, in whatever format we specify.
echo $date->format('D jS M y');
// Change the timezone to GMT.
$date->setTimezone(new DateTimeZone('GMT'));
// Now print the date/time it would in the GMT timezone
// as opposed to the default timezone it was created with.
echo $date->format('Y-m-d H:i:s');
// Just to show of some more, get the previous Sunday
$date->modify('previous Sunday');
There's a whole lot of functions you can use, that are much more readable that the procedural functions.
Explicit example of converting from a timezone to GMT
$melbourne = new DateTimeZone('Australia/Melbourne');
$gmt = new DateTimeZone('GMT');
$date = new DateTime('2011-12-25 00:00:00', $melbourne);
$date->setTimezone($gmt);
echo $date->format('Y-m-d H:i:s');
// Output: 2011-12-24 13:00:00
// At midnight on Christmas eve in Melbourne it will be 1pm on Christmas Eve GMT.
echo '<br/>';
// Convert it back to Australia/Melbourne
$date->setTimezone($melbourne);
echo $date->format('Y-m-d H:i:s');
Using your Asia/Kolkata to America/New_York
date_default_timezone_set('Asia/Kolkata');
$date = new DateTime('2011-03-28 13:00:00');
$date->setTimezone(new DateTimeZone('America/New_York'));
echo $date->format("Y-m-d H:i:s");
//Outputs: 2011-03-28 03:30:00

Answer 2

Use the gmdate function to convert to GMT time.
For example
$d = '2011-03-28 12:05:20';
$gmt = gmdate('Y-m-d H:i:s',strtotime($d));

Answer 3

// Convert local time to gmt
public function convertTime($timezone,$time){
$selectedtime = date("Y-m-d H:i",strtotime($time));
$date = new DateTime($selectedtime, new DateTimeZone($timezone));
$date->setTimezone(new DateTimeZone('GMT'));
$convertedtime = strtotime($date->format('Y-m-d H:i'));
return $convertedtime;
}