跟着视频学 c# asp.net 第三天

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace if用法
 8 {
 9     class Program
10     {
11         static void Main(string[] args)
12         {
13             Console.WriteLine("请输入用户名:");
14             string name = Console.ReadLine();
15             Console.WriteLine("请输入密码:");
16             string password = Console.ReadLine();
17             if (name == "admin" && password == "888888")
18             {
19                 Console.WriteLine("登陆成功!!!");
20 
21             }
22             else
23             {
24                 if (name != "admin")
25                 {
26                     Console.WriteLine("用户名不存在!!!");
27                     Console.WriteLine("登陆失败");
28                 }
29                 if (password != "888888")
30                 {
31                     Console.WriteLine("密码不正确!!!");
32                     Console.WriteLine("登陆失败");
33                 }
34             }
35             Console.ReadKey();
36         }
37     }
38 }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace swith用法
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("请输入月份");
            string month = Console.ReadLine();
            switch (month)
            {
                case "1":
                case "3":
                case "5":
                case "7":
                case "8":
                case "10":
                case "12":
                    Console.WriteLine("你输入的月份天数为31天!");
                    break;
                case "2":
                    Console.WriteLine("你输入的月份平年为28天,闰年为29天");
                    break;
                case "4":
                case "6":
                case "9":
                case "11":
                    Console.WriteLine("你输入的月份天数为30天!");
                    break;
                default:
                    Console.WriteLine("你输入的月份不存在!!!");
                    break;
            }
            Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace while用法
{
    class Program
    {
        static void Main(string[] args)
        {
            //输入数字,并输出输入数字的最大值
            int max = 0;
            while (true)
            {
                string num = Console.ReadLine();
                if (num == "end")
                {
                    Console.WriteLine("循环结束");
                    Console.WriteLine("输入的最大值是{0}",max);
                    Console.ReadKey();
                    return;
                }
                else
                {
                    int i = Convert.ToInt32(num);
                    if (max < i)
                    {
                        max = i;
                    }

                }

            }
           
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace for用法
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i1 = 1; i1 <= 9; i1++)
            {
                for (int i2 = 1; i2 <= 9; i2++)
                {
                    Console.WriteLine("{0}*{1}={2}", i1, i2, i1 * i2);
                }
            }
            Console.ReadKey();
        }
    }
}