Linq Grop by

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 
 5 public class Program
 6 {
 7   public static void Main()
 8   {
 9     var inputDtos = new List(){
10     new Dto{ fname = "11", lname = "12", age = "13", gender = "1"},
11 new Dto{ fname = "", lname = "12", age = "13", gender = "1"},
12 new Dto{ fname = null, lname = "12", age = "13", gender = "1"},
13 new Dto{ fname = "11", lname = "", age = "13", gender = "1"},
14 new Dto{ fname = "11", lname = null, age = "13", gender = "1"},
15 new Dto{ fname = "11", lname = "12", age = "", gender = "1"},
16 new Dto{ fname = "11", lname = "12", age = null, gender = "1"},
17 new Dto{ fname = "11", lname = "12", age = "13", gender = ""},
18 new Dto{ fname = "11", lname = "12", age = "13", gender = null},
19 
20 new Dto{ fname = "11", lname = "12", age = "13", gender = "1"},
21 new Dto{ fname = "21", lname = "22", age = "23", gender = "0"},
22 new Dto{ fname = "21", lname = "22", age = "23", gender = "0"},
23 
24 
25 };
26                      var DuplicateList = (from d in inputDtos
27                                          group d by  
28                                          new
29                                         {
30                                             firstName = TrimValueSpace(d.fname),
31                                             lastName = TrimValueSpace(d.lname),
32                                             birthday = TrimValueSpace(d.age),
33                                             gender = TrimValueSpace(d.gender)
34                                         }
35                         into gr
36                                          where gr.Count() > 1
37                                                && !string.IsNullOrWhiteSpace(gr.Key.firstName)
38                                                && !string.IsNullOrWhiteSpace(gr.Key.lastName)
39                                                && !string.IsNullOrWhiteSpace(gr.Key.birthday)
40                                                && !string.IsNullOrWhiteSpace(gr.Key.gender)
41                                          select gr.Key).ToList();
42 
43 if (DuplicateList != null )
44                         {
45           Console.WriteLine("ok  --- " + DuplicateList.Count);
46 
47                         }
48                         var sfdfd = "222";
49 
50           Console.WriteLine(sfdfd ?? "0");
51 
52 
53   }
54 
55         private static string TrimValueSpace(string value)
56         {
57             if (string.IsNullOrWhiteSpace(value))
58             {
59                 return string.Empty;
60             }
61             else
62             {
63                 return value.Replace(" ", string.Empty).Replace("　", string.Empty);
64             }
65         }
66   
67 }
68 public class Dto{
69     public string fname {get; set;}
70     public string lname {get; set;}
71     public string age{get; set;}
72     public string gender{get; set;}
73   }

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转载于:https://www.cnblogs.com/RocCnBlog/p/11176534.html