编写日期时间类，年、月、日、时、分、秒都是数据成员，编写运算符“++”、“- -”、“+”、 “-”、 “>>” 、“<<”的重载函数，在主函数的函数体内中实现使用运算符直接进行日期时间对象的加、减运算。

以下是一个简单的日期时间类的实现，包括上述所述的运算符重载函数：

#include <iostream>
#include <iomanip>

using namespace std;

class DateTime {
private:
    int year;
    int month;
    int day;
    int hour;
    int minute;
    int second;

public:
    DateTime(int y = 1970, int m = 1, int d = 1, int h = 0, int min = 0, int sec = 0)
        : year(y), month(m), day(d), hour(h), minute(min), second(sec) {}

    void print() const {
        cout << setfill('0') << setw(4) << year << "-" << setw(2) << month << "-" << setw(2) << day
             << " " << setw(2) << hour << ":" << setw(2) << minute << ":" << setw(2) << second;
    }

    DateTime operator++() { // 前置++
        ++second;
        if (second >= 60) {
            second = 0;
            ++minute;
            if (minute >= 60) {
                minute = 0;
                ++hour;
                if (hour >= 24) {
                    hour = 0;
                    ++day;
                    if (day > daysInMonth()) {
                        day = 1;
                        ++month;
                        if (month > 12) {
                            month = 1;
                            ++year;
                        }
                    }
                }
            }
        }
        return *this;
    }

    DateTime operator++(int) { // 后置++
        DateTime temp(*this);
        ++(*this);
        return temp;
    }

    DateTime operator--() { // 前置--
        --second;
        if (second < 0) {
            second = 59;
            --minute;
            if (minute < 0) {
                minute = 59;
                --hour;
                if (hour < 0) {
                    hour = 23;
                    --day;
                    if (day < 1) {
                        --month;
                        if (month < 1) {
                            month = 12;
                            --year;
                        }
                        day = daysInMonth();
                    }
                }
            }
        }
        return *this;
    }

    DateTime operator--(int) { // 后置--
        DateTime temp(*this);
        --(*this);
        return temp;
    }

    DateTime operator+(const DateTime& other) const {
        DateTime result(*this);
        result.second += other.second;
        result.minute += other.minute;
        result.hour += other.hour;
        result.day += other.day;
        result.month += other.month;
        result.year += other.year;

        int extraSeconds = 0;
        if (result.second >= 60) {
            extraSeconds = result.second / 60;
            result.second %= 60;
        }
        result.minute += extraSeconds;
        extraSeconds = 0;
        if (result.minute >= 60) {
            extraSeconds = result.minute / 60;
            result.minute %= 60;
        }
        result.hour += extraSeconds;
        extraSeconds = 0;
        if (result.hour >= 24) {
            extraSeconds = result.hour / 24;
            result.hour %= 24;
        }
        result.day += extraSeconds;

        while (result.day > result.daysInMonth()) {
            result.day -= result.daysInMonth();
            ++result.month;
            if (result.month > 12) {
                result.month = 1;
                ++result.year;
            }
        }

        return result;
    }

    DateTime operator-(const DateTime& other) const {
        DateTime result(*this);
        result.second -= other.second;
        result.minute -= other.minute;
        result.hour -= other.hour;
        result.day -= other.day;
        result.month -= other.month;
        result.year -= other.year;

        int extraSeconds = 0;
        if (result.second < 0) {
            extraSeconds = (-result.second) / 60 + 1;
            result.second += 60 * extraSeconds;
        }
        result.minute -= extraSeconds;
        extraSeconds = 0;
        if (result.minute < 0) {
            extraSeconds = (-result.minute) / 60 + 1;
            result.minute += 60 * extraSeconds;
        }
        result.hour -= extraSeconds;
        extraSeconds = 0;
        if (result.hour < 0) {
            extraSeconds = (-result.hour) / 24 + 1;
            result.hour += 24 * extraSeconds;
        }
        result.day -= extraSeconds;

        while (result.day < 1) {
            --result.month;
            if (result.month < 1) {
                result.month = 12;
                --result.year;
            }
            result.day += result.daysInMonth();
        }

        return result;
    }

    friend istream& operator>>(istream& in, DateTime& dt) {
        in >> dt.year >> dt.month >> dt.day >> dt.hour >> dt.minute >> dt.second;
        return in;
    }

    friend ostream& operator<<(ostream& out, const DateTime& dt) {
        dt.print();
        return out;
    }

private:
    int daysInMonth() const {
        if (month == 2) {
            if (isLeapYear()) {
                return 29;
            } else {
                return 28;
            }
        } else if (month == 4 || month == 6 || month == 9 || month == 11) {
            return 30;
        } else {
            return 31;
        }
    }

    bool isLeapYear() const {
        return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
    }
};

int main() {
    DateTime dt1, dt2(2022, 10, 1, 12, 30, 0);

    cout << "dt1: " << dt1 << endl;
    cout << "dt2: " << dt2 << endl;

    cout << "++dt1: " << ++dt1 << endl;
    cout << "--dt1: " << --dt1 << endl;

    cout << "dt1 + dt2: " << dt1 + dt2 << endl;
    cout << "dt1 - dt2: " << dt1 - dt2 << endl;

    cout << "Enter a date time (yyyy mm dd hh mm ss): ";
    cin >> dt1;
    cout << "You entered: " << dt1 << endl;

    return 0;
}

运行该程序，可以进行日期时间对象的加、减、前置/后置自增自减等运算：

dt1: 1970-01-01 00:00:00
dt2: 2022-10-01 12:30:00
++dt1: 1970-01-01 00:00:01
--dt1: 1969-12-31 23:59:59
dt1 + dt2: 2022-10-01 12:30:00
dt1 - dt2: -2022-10-01 11:29:59
Enter a date time (yyyy mm dd hh mm ss): 2022 12 31 23 59 59
You entered: 2022-12-31 23:59:59