code: private function format_c(&$str) {
      if (strstr($str, '%c'))
        if ($this->dayFrac == 0)
          $str = str_replace('%c', "{$this->day}.0", $str);
        else
          $str = str_replace('%c', round($this->day + $this->dayFrac, 7), $str);
    }
docs: Day without leading zero and fraction (added for AstroDate)
  @param type $str