请用枚举法编写C++及C#代码，并附注详细注释

C++代码：

#include <iostream>

using namespace std;

// 枚举类型，表示星期几
enum Weekday {
    Sunday,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday
};

int main()
{
    // 定义星期几变量并初始化为星期一
    Weekday today = Monday;

    // 输出今天是星期几
    switch (today) {
        case Sunday:
            cout << "Today is Sunday." << endl;
            break;
        case Monday:
            cout << "Today is Monday." << endl;
            break;
        case Tuesday:
            cout << "Today is Tuesday." << endl;
            break;
        case Wednesday:
            cout << "Today is Wednesday." << endl;
            break;
        case Thursday:
            cout << "Today is Thursday." << endl;
            break;
        case Friday:
            cout << "Today is Friday." << endl;
            break;
        case Saturday:
            cout << "Today is Saturday." << endl;
            break;
    }

    return 0;
}

C#代码：

using System;

// 枚举类型，表示星期几
enum Weekday {
    Sunday,
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday
}

class Program
{
    static void Main(string[] args)
    {
        // 定义星期几变量并初始化为星期一
        Weekday today = Weekday.Monday;

        // 输出今天是星期几
        switch (today) {
            case Weekday.Sunday:
                Console.WriteLine("Today is Sunday.");
                break;
            case Weekday.Monday:
                Console.WriteLine("Today is Monday.");
                break;
            case Weekday.Tuesday:
                Console.WriteLine("Today is Tuesday.");
                break;
            case Weekday.Wednesday:
                Console.WriteLine("Today is Wednesday.");
                break;
            case Weekday.Thursday:
                Console.WriteLine("Today is Thursday.");
                break;
            case Weekday.Friday:
                Console.WriteLine("Today is Friday.");
                break;
            case Weekday.Saturday:
                Console.WriteLine("Today is Saturday.");
                break;
        }
    }
}

注释：

1. `enum Weekday`：定义枚举类型 Weekday，表示星期几。
2. `Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday`：枚举类型的值。
3. `Weekday today = Monday;`：定义变量 today，类型为 Weekday，初始值为 Monday。
4. `switch (today)`：根据变量 today 的值执行相应的分支。
5. `case Sunday:`：如果 today 的值为 Sunday，则执行下面的语句。
6. `cout << "Today is Sunday." << endl;`：输出今天是星期几。
7. `break;`：跳出 switch 语句。
8. 其他 case 分支和说明与上面类似。
9. `return 0;`：结束程序。
10. C#代码与C++代码类似，只是语法略有不同。