php convert datetime to UTC

Question

I am in need of an easy way to convert a date time stamp to UTC (from whatever timezone the server is in) HOPEFULLY without using any libraries.

Answer 1

As strtotime requires specific input format, DateTime::createFromFormat could be used (php 5.3+ is required)

// set timezone to user timezone
date_default_timezone_set($str_user_timezone);

// create date object using any given format
$date = DateTime::createFromFormat($str_user_dateformat, $str_user_datetime);

// convert given datetime to safe format for strtotime
$str_user_datetime = $date->format('Y-m-d H:i:s');

// convert to UTC
$str_UTC_datetime = gmdate($str_server_dateformat, strtotime($str_user_datetime));

// return timezone to server default
date_default_timezone_set($str_server_timezone);