app/Date/AbstractCalendarDate.php
protected function formatDayZeros(): string
    {
        if ($this->day > 9) {
            return I18N::digits($this->day);
        }

        return I18N::digits('0' . $this->day);
    }
protected function formatDayZeros(): string
    {
        if ($this->day > 9) {
            return I18N::digits($this->day);
        }

        return I18N::digits('0' . $this->day);
    }
protected function formatDayZeros ( ) : string { if ( $ this -> day > 9 ) { return I18N :: digits ( $ this -> day ) ; } return I18N :: digits ( '0' . $ this -> day ) ; }
Generate the %d format for a date.

@return string
Generate the %d format for a date .