[C++]연산자 오버로딩

Delegation

	bool operator==(Date& rhs) {
		return year == rhs.year && month == rhs.month && day == rhs.day;
	}
	bool operator !=(Date& rhs) {
		return !(*this == rhs);
	}

delegation 한 것을 볼 수 있습니다. 

 

#include <iostream>
#include <fstream>
#include <vector>
#include <istream>
#include <algorithm>
using namespace std;

class Date {
private:
	int year, month, day;
	vector<int> short_months{ 4, 6, 9, 11 };
	bool is_short_month() {
		return find(short_months.begin(), short_months.end(), month)
			!= short_months.end();
	}
	bool last_day_of_month() {
		return month == 2 && day == 28 || is_short_month() && day == 30
			|| day == 31;
	}
	bool last_day_of_year() {
		return month == 12 && day == 31;
	}
public:
	Date() = default;
	Date(int y, int m, int d) : year(y), month(m), day(d) {}

	bool operator<(Date& rhs) {
		return year < rhs.year ||
			(year == rhs.year && month < rhs.month) ||
			(year == rhs.year && month == rhs.month && day < rhs.day);
	}
	bool operator>(Date& rhs) {
		return year > rhs.year ||
			(year == rhs.year && month > rhs.month) ||
			(year == rhs.year && month == rhs.month && day > rhs.day);
	}
	bool operator==(Date& rhs) {
		return year == rhs.year && month == rhs.month && day == rhs.day;
	}
	bool operator !=(Date& rhs) {
		return !(*this == rhs);
	}
	bool operator<=(Date& rhs) {
		return *this < rhs || *this == rhs;
	}
	bool operator>=(Date& rhs) {
		return *this > rhs || *this == rhs;
	}
	Date& operator++() { //전위연산자
		if (last_day_of_year()) {
			year++, month = 1, day = 1;
		}
		else if (last_day_of_month()) {
			month++; day = 1;
		}
		else {
			day++;
		}
		return *this;
	}
	Date operator++(int) { //int는 후위연산자를 표시하는 방식
		Date ret = *this; //후위 ++연산자는 연산 수행 전의 값을 반환해야 하므로 먼저 현재의 객체를 복사해 둔다.
		if (last_day_of_year()) {
			year++, month = 1, day = 1;
		}
		else if (last_day_of_month()) {
			month++; day = 1;
		}
		else {
			day++;
		}
		return ret;  //복사해 둔 객체는 이 함수가 종료되면 소멸되므로 복사에 의한 return을 해줘야한다.  
	}
	int operator-(Date& rhs) {
		if (*this == rhs)
			return 0;
		else if (*this < rhs) {
			Date temp = *this;
			int diff = 0;
			while (temp < rhs) {
				temp++;
				diff++;
			}
			return -diff;
		}
		else {
			Date temp = rhs;
			int diff = 0;
			while (*this > temp) {
				temp++;
				diff++;
			}
			return diff;
		}
	}
	Date operator+(int k)
	{
		Date temp = *this;
		for (int i = 0; i < k; i++)
			++temp;
		return temp;
	}
	void pirnt(ostream& out) {
		out << year << "/" << month << "/" << day;
	}

	void sort_dates(vector<Date>& dates) {
		for (int i = dates.size() - 1; i > 0; i--) {
			for (int j = 0; j < i; j++)
			{
				if (dates.at(j) > dates.at(j + 1))
					swap(dates.at(j), dates.at(j + 1));
			}
		}
	}

};

int main() {
	vector<Date> dates;
	ifstream("dates.txt");
	int y, m, d;
	while (infile >> y >> m >> d)
	{
		dates.push_back(Date(y, m, d));
	}
	infile.close();

	sort_dates(dates);

	for (Date& d : dates) {
		d.print(cout);
		cout << endl;
	}

	cin >> y >> m >> d;
	Date theDay(y, m, d);
	int min_diff = abs(dates[0] - theDay);
	Date closest_day = dates[0];
	for (Date& dt : dates) {
		int diff = abs(dt - theDay);
		if (diff < min_diff) {
			min_diff = diff;
			closest_day = dt;
		}
	}
	closest_day.print(cout);
	cout << "with difference " << min_diff << "days " << endl;
	return 0;
}