构造一个日期类Date要求重载：流提取和流插入运算符重载前置和后置自增运算符

#include <iostream>
using namespace std;

class Date {
private:
    int year, month, day;
public:
    Date(int y = 1970, int m = 1, int d = 1) {
        year = y;
        month = m;
        day = d;
    }
    friend ostream& operator<<(ostream& os, const Date& date) {
        os << date.year << '-' << date.month << '-' << date.day;
        return os;
    }
    friend istream& operator>>(istream& is, Date& date) {
        is >> date.year >> date.month >> date.day;
        return is;
    }
    Date& operator++() { // 前置自增
        day++;
        if (day > getMonthDays()) {
            day = 1;
            month++;
            if (month > 12) {
                month = 1;
                year++;
            }
        }
        return *this;
    }
    Date operator++(int) { // 后置自增
        Date date(*this);
        day++;
        if (day > getMonthDays()) {
            day = 1;
            month++;
            if (month > 12) {
                month = 1;
                year++;
            }
        }
        return date;
    }
    int getMonthDays() const {
        if (month == 2) {
            if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
                return 29;
            }
            else {
                return 28;
            }
        }
        else if (month == 4 || month == 6 || month == 9 || month == 11) {
            return 30;
        }
        else {
            return 31;
        }
    }
};

int main() {
    Date date(2022, 12, 31);
    cout << date++ << endl; // 后置自增
    cout << ++date << endl; // 前置自增
    return 0;
}
``