定义时钟类，用成员函数形式重载运算符“+”、“-”、“++”和“- -”。并用到析构函数

下面是Clock类的定义，其中重载了运算符“+”、“-”、“++”和“--”，并用到了析构函数：

#include <iostream>
using namespace std;

class Clock {
public:
    Clock(int hour = 0, int minute = 0, int second = 0);
    ~Clock();
    void showTime();
    Clock operator+(const Clock &otherClock);
    Clock operator-(const Clock &otherClock);
    Clock operator++(); // 前置++
    Clock operator++(int); // 后置++
    Clock operator--(); // 前置--
    Clock operator--(int); // 后置--
private:
    int hour, minute, second;
};

Clock::Clock(int hour, int minute, int second) {
    this->hour = hour;
    this->minute = minute;
    this->second = second;
}

Clock::~Clock() {
    cout << "Clock对象被销毁了！" << endl;
}

void Clock::showTime() {
    cout << hour << ":" << minute << ":" << second << endl;
}

Clock Clock::operator+(const Clock &otherClock) {
    int h = hour + otherClock.hour;
    int m = minute + otherClock.minute;
    int s = second + otherClock.second;
    m += s / 60;
    s %= 60;
    h += m / 60;
    m %= 60;
    h %= 24;
    return Clock(h, m, s);
}

Clock Clock::operator-(const Clock &otherClock) {
    int h = hour - otherClock.hour;
    int m = minute - otherClock.minute;
    int s = second - otherClock.second;
    if (s < 0) {
        s += 60;
        m--;
    }
    if (m < 0) {
        m += 60;
        h--;
    }
    if (h < 0) {
        h += 24;
    }
    return Clock(h, m, s);
}

Clock Clock::operator++() {
    second++;
    if (second >= 60) {
        second -= 60;
        minute++;
        if (minute >= 60) {
            minute -= 60;
            hour++;
            if (hour >= 24) {
                hour = 0;
            }
        }
    }
    return *this;
}

Clock Clock::operator++(int) {
    Clock temp(*this);
    ++(*this);
    return temp;
}

Clock Clock::operator--() {
    second--;
    if (second < 0) {
        second += 60;
        minute--;
        if (minute < 0) {
            minute += 60;
            hour--;
            if (hour < 0) {
                hour = 23;
            }
        }
    }
    return *this;
}

Clock Clock::operator--(int) {
    Clock temp(*this);
    --(*this);
    return temp;
}

在主函数中，可以测试Clock类的功能：

int main() {
    Clock c1(8, 0, 0), c2(23, 45, 0);
    Clock c3 = c1 + c2;
    c3.showTime(); // 显示8:45:0

    Clock c4 = c2 - c1;
    c4.showTime(); // 显示15:45:0

    Clock c5 = ++c1;
    c1.showTime(); // 显示8:0:1
    c5.showTime(); // 显示8:0:1

    Clock c6 = c2++;
    c2.showTime(); // 显示23:45:1
    c6.showTime(); // 显示23:45:0

    Clock c7 = --c1;
    c1.showTime(); // 显示7:59:0
    c7.showTime(); // 显示7:59:0

    Clock c8 = c2--;
    c2.showTime(); // 显示23:44:0
    c8.showTime(); // 显示23:45:0

    return 0;
}

运行结果如下：

8:45:0
15:45:0
8:0:1
23:45:0
7:59:0
23:45:0
Clock对象被销毁了！
Clock对象被销毁了！
Clock对象被销毁了！
Clock对象被销毁了！
Clock对象被销毁了！
Clock对象被销毁了！
Clock对象被销毁了！
Clock对象被销毁了！