private function format_j(&$str) {
    if (strstr($str, '%j'))
      $str = str_replace('%j', sprintf('%01d', $this->day), $str);
  }
private function format_j(&$str) {
    if (strstr($str, '%j'))
      $str = str_replace('%j', sprintf('%01d', $this->day), $str);
  }
Day of the month without leading zeros
@param type $str