By using Julian day count ( Integer value ) we can get the calendar details like month , day , day of the week, year etc ( in the form of an array ). Syntax is here.
Here is an example
The output is here
$jdday_number = cal_to_jd(CAL_JULIAN,12,4,2013);
Array ( [date] => 12/4/2013 [month] => 12 [day] => 4 [year] => 2013 [dow] => 2 [abbrevdayname] => Tue [dayname] => Tuesday [abbrevmonth] => Dec [monthname] => December )