Timespan

function timespan($time1, $time2 = NULL, $output = 'years,months,weeks,days,hours,minutes,seconds')
{
	// Array with the output formats
	$output = preg_split('/[^a-z]+/', strtolower((string) $output));
		// Invalid output
	if (empty($output))
		return FALSE;
		// Make the output values into keys
	extract(array_flip($output), EXTR_SKIP);
		// Default values
	$time1  = max(0, (int) $time1);
	$time2  = empty($time2) ? time() : max(0, (int) $time2);
		// Calculate timespan (seconds)
	$timespan = abs($time1 - $time2);
		// All values found using Google Calculator.
	// Years and months do not match the formula exactly, due to leap years.
		// Years ago, 60 * 60 * 24 * 365
	isset($years) and $timespan -= 31556926 * ($years = (int) floor($timespan / 31556926));
		// Months ago, 60 * 60 * 24 * 30
	isset($months) and $timespan -= 2629744 * ($months = (int) floor($timespan / 2629743.83));
		// Weeks ago, 60 * 60 * 24 * 7
	isset($weeks) and $timespan -= 604800 * ($weeks = (int) floor($timespan / 604800));
		// Days ago, 60 * 60 * 24
	isset($days) and $timespan -= 86400 * ($days = (int) floor($timespan / 86400));
		// Hours ago, 60 * 60
	isset($hours) and $timespan -= 3600 * ($hours = (int) floor($timespan / 3600));
		// Minutes ago, 60
	isset($minutes) and $timespan -= 60 * ($minutes = (int) floor($timespan / 60));
		// Seconds ago, 1
	isset($seconds) and $seconds = $timespan;
		// Remove the variables that cannot be accessed
	unset($timespan, $time1, $time2);
		// Deny access to these variables
	$deny = array_flip(array('deny', 'key', 'difference', 'output'));
		// Return the difference
	$difference = array();
	foreach ($output as $key)
	{
		if (isset($$key) AND ! isset($deny[$key]))
		{
			// Add requested key to the output
			$difference[$key] = $$key;
		}
	}
		// Invalid output formats string
	if (empty($difference))
		return FALSE;
		// If only one output format was asked, don't put it in an array
	if (count($difference) === 1)
		return current($difference);
		// Return array
	return $difference;
}