Character Description
c ISO-8601 format (YYYY-MM-DDTHH:MM:SS±HHMM, for example, 2005-03-14T19:38:08+10:00).
r RFC-2822 format WWW, DD MMM YYYY HH:MM:SS ±HHMM, for example, Mon, 14 Mar 2005 19:38:08 +1000).
U Seconds since the Unix epoch. Calling date('U')with no timestamp argument produces the same output as the time()function.