c#基础

using System;
using System.Globalization;

class Program
{
    public static void Main(string[] args)
    {
        var year = GetInt();
        var month = GetMonth();
        var days = 0;
        switch (month)
        {
            case 4:
            case 6:
            case 9:
            case 11:
                days = 30;
                break;
            case 2:
                days = IsLeapYear(year) ? 29 : 28;
                break;
            default:
                days = 31;
                break;
        }
        print(days);
    } //Main函数结束

    /// <summary>
    /// 获得一个正确的月份
    /// </summary>
    /// <returns></returns>
    private static int GetMonth()
    {
        var m = 0;
        while (true)
        {
            m = GetInt();
            if (m > 12 || m < 0)
            {
                print("输入的月份有误,请重新输入!");
            }
            else
            {
                break;
            }
        }
        return m;
    }

    /// <summary>
    /// 判断给定的年份是否是闰年
    /// </summary>
    /// <param name="year"></param>
    /// <returns></returns>
    public static bool IsLeapYear(int year)
    {
        return year % 400 == 0 || year % 4 == 0 && year % 100 != 0;
    }

    #region 工具方法

    public static void print(string obj, params object[] arg)
    {
        Console.WriteLine(obj, arg);
    }

    public static void print(object obj)
    {
        Console.WriteLine(obj);
    }

    /// <summary>
    /// 获得一个int类型的值
    /// </summary>
    /// <returns></returns>
    public static int GetInt()
    {
        int i;
        while (true)
        {
            try
            {
                i = Convert.ToInt32(Console.ReadLine());
                break;
            }
            catch (FormatException e)
            {
                Console.WriteLine(e.Message);
            }
        }
        return i;
    }

    public static string GetString()
    {
        return Console.ReadLine();
    }

    public static double GetDouble()
    {
        double i;
        while (true)
        {
            try
            {
                i = Convert.ToDouble(Console.ReadLine());
                break;
            }
//            catch
            catch (FormatException e)
            {
                Console.WriteLine(e.Message);
            }
        }
        return i;
    }

    #endregion
}