//---------------------------------------------------
//operator>
//overwrite the operator>
//@param book the book that compare to
//@return true if grater than, false if smaller
bool Periodical::operator>(const Publication& book)const{
	if(year > book.getYear()) return true;                 //year is greater
	else if(year == book.getYear()){                       //year is equal -> check month
		if(month > book.getMonth()) return true;           //month is greater
		else if(month == book.getMonth()){                 //month is equal -> check title
			return thisBookTitle > book.getTitle();
		}else
			return false;                                  //month is smaller
	}else                                                  //year is smaller
		return false;
}
//---------------------------------------------------
//operator==
//overwrite the operator==
//@param book the book that compare to
//@return true if equals, false if not
bool Periodical::operator==(const Publication& book)const{
	return (year == book.getYear() && month == book.getMonth()
		&& thisBookTitle == book.getTitle() && thisBookType == book.getType());
}