CODE EXAMPLE FOR PHP

php get date from day of year

// This should get you a DateTime object from the date and year.
function getDateFromDay($dayOfYear, $year) {
  $date = DateTime::createFromFormat('z Y', strval($dayOfYear) . ' ' . strval($year));
  return $date;
}

// This should get you the day of the year and the year in a string.
date('z Y', strtotime('21 oct 2012'));