private function format_d(&$str) {
    if (strstr($str, '%d'))
      $str = str_replace('%d', sprintf('%02d', $this->day), $str);
  }
private function format_d(&$str) {
    if (strstr($str, '%d'))
      $str = str_replace('%d', sprintf('%02d', $this->day), $str);
  }
private function format_d ( & $ str ) { if ( strstr ( $ str , '%d' ) ) $ str = str_replace ( '%d' , sprintf ( '%02d' , $ this -> day ) , $ str ) ; }
Day of the month, 2 digits with leading zeros
@param string $str
Day of the month 2 digits with leading zeros