How to retrieve timezone offset from GMT+0 in php?

getStandardOffsetUTC.php

<?php

public function getStandardOffsetUTC($timezone)
{
	if($timezone == 'UTC') {
		return '';
	} else {
		$timezone = new DateTimeZone($timezone);
		$transitions = array_slice($timezone->getTransitions(), -3, null, true);

		foreach (array_reverse($transitions, true) as $transition)
		{
			if ($transition['isdst'] == 1)
			{
				continue;
			}

			return sprintf('UTC %+03d:%02u', $transition['offset'] / 3600, abs($transition['offset']) % 3600 / 60);
		}

		return false;
	}
}

// usage
echo getStandardOffsetUTC('Europe/Sofia');