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; } = 0;
        //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 1 + 1;
        }
 
       //新特性还是用Lambda的语法而已
        public int AddNew() => 1+1;
        public int AddNew(int a) => 1 + 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(2));
            //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(1);
                    break;
                case null:
                    Console.WriteLine(2);
                    break;
               
                default:
                    Console.WriteLine(3);
                    break;
            }
            //var tuple = (1, 2);                           // 使用语法糖创建元组
            var tuple2 = Tuple.Create(1, 2);         // 使用静态方法【Create】创建元组
            var tuple3 = new Tuple<int, int>(1, 2);  // 使用 new 运算符创建元组
            Tuple<int, int> r = Divide(13, 2);
            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", 78),
                      new Tuple<string, Nullable<int>>("Abbey", 92),
                      new Tuple<string, Nullable<int>>("Dave", 88),
                      new Tuple<string, Nullable<int>>("Sam", 91),
                      new Tuple<string, Nullable<int>>("Ed", null),
                      new Tuple<string, Nullable<int>>("Penelope", 82),
                      new Tuple<string, Nullable<int>>("Linda", 99),
                      new Tuple<string, Nullable<int>>("Judith", 84) };
            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>(0, "Sucess");
        }


        private static double ComputeMean(Tuple<string, Nullable<int>>[] scores, out int n)
        {
            n = 0;
            int sum = 0;
            foreach (var score in scores)
            {
                if (score.Item2.HasValue)
                {
                    n += 1;
                    sum += score.Item2.Value;
                }
            }
            if (n > 0)
                return sum / (double)n;
            else
                return 0;
        }

    }



}