c# 敏捷2 ForEach ToDictionary ToLookup Except比较

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 
 namespace ConsoleApplication2
 {
 
     class Program
     {
         public  class post
         {
             public string id { get; set; }
             public string name { get; set; }
             public int age { get; set; }
             public string pd { get; set; }
         }
         static void Main(string[] args)
         {
             var product = new List<post>
           {
                 new post { name=""},
                 new post { name=""},
                 new post { name=""},
                 new post { name=""},
           };
             product.ToList().ForEach(a => a.id = Guid.NewGuid().ToString("N"));//进行遍历赋值
 
             var pp = product.ToDictionary(a => a.name, a => a.id); //转成字典
             Console.WriteLine(pp.FirstOrDefault().Key + " " + pp.FirstOrDefault().Value);
 
             product.Add(new post { name = "", id = Guid.NewGuid().ToString("N") });
             var pd = product.ToLookup(a => a.name, a => a.id);//groupby之后转成字典，取不同项
             Console.WriteLine(pp.FirstOrDefault().Key + " " + pp.FirstOrDefault().Value);
 
             var pro = new List<post>
           {
                 new post { id = Guid.NewGuid().ToString("N"),name="",age=,pd="sad"},
                 new post { id = Guid.NewGuid().ToString("N"),name="",age=,pd="sad"},
                 new post { id = Guid.NewGuid().ToString("N"),name="",age=,pd="sad"},
                 new post {id = Guid.NewGuid().ToString("N"), name="",age=,pd="sad"},
           };
             var prd = new List<post>
           {
                 new post { id = Guid.NewGuid().ToString("N"),name="",age=,pd="sad"},
                 new post { id = Guid.NewGuid().ToString("N"),name="",age=,pd="sad"},
                 new post {id = Guid.NewGuid().ToString("N"), name="",age=,pd="sad"},
                 new post {id = Guid.NewGuid().ToString("N"), name="",age=,pd="sad"},
           };
             var dsz = pro.Select(s => new { id = s.age, name = s.name, pd = s.pd });
             var dsx = prd.Select(s => new { id = s.age, name = s.name, pd = s.pd });
             var dsc = dsz.Except(dsx).Count();
             if (dsc > )
                 Console.WriteLine("修改过");
             else
                 Console.WriteLine("未修改");
 
             if (pro.Select(s => new { id = s.age, name = s.name, pd = s.pd }).Except(prd.Select(s => new { id = s.age, name = s.name, pd = s.pd })).Count() > )
                 Console.WriteLine("修改过");
             else
                 Console.WriteLine("未修改");
             Console.WriteLine(dsc);
 
             Console.Read();
 
         }
 
     }
 
 }