Llinq Except and How it Differs from Not In Operator

Contains & Except

using System;  
 using System.Collections.Generic;  
 using System.Linq;  
 namespace LinqDetails  
 {  
   class Program  
   {  
     static void Main(string[] args)  
     {  
       List<int> num1 = new List<int> { 1,4,7,12};  
       List<int> num2 = new List<int> { 1, 9, 7, 13 };  
       List<int> final = num2.Where(x => !num1.Contains(x)).ToList();//9 13  
       foreach (var items in final)  
       {  
         Console.WriteLine(items);  
       }  
       Console.WriteLine("=======Except Begins=======");  
       List<int> final1 = num2.Except(num1).ToList();//9 13  
       foreach (var items in final1)  
       {  
         Console.WriteLine(items);  
       }  
       Console.ReadLine();  
     }  
   }  

 

• Both output is 9 and 13
• First One is Not In operator :- x not there in num1.
• Second one is Except

===================================================================

Now lets make some twist
Code

 class Program  
   {  
     static void Main(string[] args)  
     {  
       List<int> num1 = new List<int> { 1,4,7,12};  
       List<int> num2 = new List<int> { 1, 9, 7, 13,13 };  
       List<int> final = num2.Where(x => !num1.Contains(x)).ToList();//9 13 13  
       foreach (var items in final)  
       {  
         Console.WriteLine(items);  
       }  
       Console.WriteLine("=======Except Begins=======");  
       List<int> final1 = num2.Except(num1).ToList();//9 13  
       foreach (var items in final1)  
       {  
         Console.WriteLine(items);  
       }  
       Console.ReadLine();  
     }     

Output

• Except always gives distinct values

====================================================================


 Lets try with a List of Classes

using System;   
  using System.Collections.Generic;   
  using System.Linq;   
  namespace LinqDetails   
  {   
   class list1   
   {   
    public string FirstName { get; set; }   
    public string Id { get; set; }   
   }   
   class list2   
   {   
    public string FirstName { get; set; }   
    public string Id { get; set; }   
   }   
   class Program   
   {   
    static void Main(string[] args)   
    {   
     List<list1> list1 = new List<list1>();   
     List<list2> list2 = new List<list2>();   
     list1.Add(new list1 { FirstName="Biswa", Id="1" });   
     list1.Add(new list1 { FirstName = "Anurag", Id = "2" });   
     list1.Add(new list1 { FirstName="Prasad", Id="3" });   
     list2.Add(new list2 { FirstName = "Abhi", Id = "1" });   
     list2.Add(new list2 { FirstName = "Anurag", Id = "2" });   
     list2.Add(new list2 { FirstName = "Siba", Id = "3" });   
     List<list2> list2NotInList1 = list2.Where(x => !list1.Any(y => y.FirstName == x.FirstName)).ToList();   
     foreach (list2 list in list2NotInList1)   
     {   
      Console.WriteLine(list.FirstName + " " + list.Id);   
     }   
     Console.ReadLine();   
    }   
   }   
  }   

ANY

• Using Any for the first scenario

            List<int> num1 = new List<int> { 1,4,7,12};
            List<int> num2 = new List<int> { 1, 9, 7, 13 };
            List<int> final3 = num2.Where(x => !num1.Any(y=>y==x)).ToList();//9 13

• If duplicate is there then it takes duplicate value too.

            List<int> num1 = new List<int> { 1,4,7,12};
            List<int> num2 = new List<int> { 1, 9, 7, 13,13 };
            List<int> final = num2.Where(x => !num1.Contains(x)).ToList();//9 13 13
            List<int> finalAny = num2.Where(x => !num1.Any(y => y == x)).ToList();// 9 13 13
            

• To Make it distinct use below code

List<int> final = num2.Where(x => !num1.Any(y=>y==x)).Distinct().ToList();// 9 13


=====================================================================


I hope you enjoyed the things  :)