如何制作一个万年历程序

这是一个使用C++语言编写的万年历程序，可以让用户输入年份和月份来查看对应的日历。

#include <iostream>
using namespace std;

int main() {
    int year, month, daysInMonth, startDay;
    cout << "请输入年份：";
    cin >> year;
    cout << "请输入月份：";
    cin >> month;

    // 计算该月有多少天
    if (month == 2) {
        if (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0)) {
            daysInMonth = 29;
        } else {
            daysInMonth = 28;
        }
    } else if (month == 4 || month == 6 || month == 9 || month == 11) {
        daysInMonth = 30;
    } else {
        daysInMonth = 31;
    }

    // 计算该月第一天是星期几
    int century = year / 100;
    int yearOfCentury = year % 100;
    startDay = (1 + 2 * (3 - (century % 4))) * (yearOfCentury + yearOfCentury / 4) % 7;

    // 输出日历
    cout << "日\t一\t二\t三\t四\t五\t六\n";
    for (int i = 0; i < startDay; i++) {
        cout << "\t";
    }
    for (int i = 1; i <= daysInMonth; i++) {
        cout << i << "\t";
        if ((i + startDay) % 7 == 0) {
            cout << endl;
        }
    }
    cout << endl;

    return 0;
}
</iostream>