php返回相对时间，如：20分钟前，3天前

php返回相对时间，如：20分钟前，3天前

function plural($num) {
	if ($num != 1)
		return "s";
}
 
function getRelativeTime($date) {
	$diff = time() - strtotime($date);
	if ($diff<60)
		return $diff . " second" . plural($diff) . " ago";
	$diff = round($diff/60);
	if ($diff<60)
		return $diff . " minute" . plural($diff) . " ago";
	$diff = round($diff/60);
	if ($diff<24)
		return $diff . " hour" . plural($diff) . " ago";
	$diff = round($diff/24);
	if ($diff<7)
		return $diff . " day" . plural($diff) . " ago";
	$diff = round($diff/7);
	if ($diff<4)
		return $diff . " week" . plural($diff) . " ago";
	return "on " . date("F j, Y", strtotime($date));
}