C# 敏捷1

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

 namespace ConsoleApplication2
 {
     public class Post
     {
         public string Title { get;  set; } = "Title";
         public string Content { get;  set; }= "Content";

         public int? age { get; set; } = ;
         //新特性
         public DateTime DateCreated { get; private set; } = DateTime.Now;
         public List<Comment> Comments { get; private set; } = new List<Comment>();
         public int AddOld()
         {
             return  + ;
         }

        //新特性还是用Lambda的语法而已
         public int AddNew() => +;
         public int AddNew(int a) =>  + a;

     }

     public class Comment
     {

     }
     class Program
     {

         static void Main(string[] args)
         {
             var dictionary = new Dictionary<string, string>
               {
                    { "key1","value1"},
                     { "key2","value2"}
                };

             //新特性
             var dictionary1 = new Dictionary<string, string>
             {
                 ["key1"] = "value1",
                 ["key2"] = "value2"
             };
             Console.WriteLine(dictionary);

             Post post = new Post();

             string t1 = string.Format("{0}_{1}", post.Title, post.Content);
             //新特性
             string t2 = $"{post.Title}_{post.Content}";
             Console.Write(t1); Console.Write("-"); Console.WriteLine(t2);

             Console.Write(post.AddOld());   Console.WriteLine(post.AddNew());
             //if (x in (1, 2, 3)) 
             //if (x in 1:5)
             //if (x between(1, 5))

             List<Tuple<string, string, string>> result = new List<Tuple<string, string, string>>();
             result.Add(new Tuple<string, string, string>("fa", "q："  , ""));

             string obj = null ;

             switch (obj)
             {
                 case "+" :
                     Console.WriteLine();
                     break;
                 case null:
                     Console.WriteLine();
                     break;

                 default:
                     Console.WriteLine();
                     break;
             }
             //var tuple = (1, 2);                           // 使用语法糖创建元组
             var tuple2 = Tuple.Create(, );         // 使用静态方法【Create】创建元组
             var tuple3 = new Tuple<int, int>(, );  // 使用 new 运算符创建元组
             Tuple<int, int> r = Divide(, );
             Console.WriteLine($"{r.Item1}_{r.Item2}");
             var z = M();
             Console.WriteLine($"{z.Item1}_{z.Item2}");

             Tuple<string, Nullable<int>>[] scores =
                     { new Tuple<string, Nullable<int>>("Jack", ),
                       new Tuple<string, Nullable<int>>("Abbey", ),
                       new Tuple<string, Nullable<int>>("Dave", ),
                       new Tuple<string, Nullable<int>>("Sam", ),
                       new Tuple<string, Nullable<int>>("Ed", null),
                       new Tuple<string, Nullable<int>>("Penelope", ),
                       new Tuple<string, Nullable<int>>("Linda", ),
                       new Tuple<string, Nullable<int>>("Judith", ) };
             int number;
             double mean = ComputeMean(scores, out number);
             Console.WriteLine("Average test score: {0:N2} (n={1})", mean, number);

             Console.ReadKey(true);
         }
         public static Tuple<int, int> Divide(int dividend, int divisor)
         {
             int result = dividend / divisor;
             int reminder = dividend % divisor;
             return Tuple.Create<int, int>(result, reminder);           //返回两个相同类型元素的元组
         }
         public static Tuple<int, string> M()
         {
             Tuple<int, string> tuple = null;
             return tuple = new Tuple<int, string>(, "Sucess");
         }

         private static double ComputeMean(Tuple<string, Nullable<int>>[] scores, out int n)
         {
             n = ;
             int sum = ;
             foreach (var score in scores)
             {
                 if (score.Item2.HasValue)
                 {
                     n += ;
                     sum += score.Item2.Value;
                 }
             }
             if (n > )
                 return sum / (double)n;
             else
                 return ;
         }

     }

 }