Find the number that don't exist in another array

Question

I need to find the values in array A that don't exist in array B

A = {1,2,3,4,5,6,7,8,9,10}

B = {1,2,3,7,8}

result = {4,5,6,9,10}

Can anyone give me any pointers?

Possible duplicate of http://stackoverflow.com/questions/801757/disjoint-union-in-linq — Bort, Feb 02 '12 at 18:18
http://stackoverflow.com/questions/8975969/c-sharp-linq-get-elements-from-array-which-do-not-exist-in-a-different-array — Jimmy, Feb 02 '12 at 18:23
@puria Typically, highest voted or first-in wins. Whichever you found most helpful to your needs. — Yuck, Feb 02 '12 at 18:25

H H · Accepted Answer · 2012-02-02T18:39:00.050

14

Using LINQ:

  var C = A.Except(B);

or, if you want it as an array:

  int[] C = A.Except(B).ToArray();

edited Feb 02 '12 at 18:39

answered Feb 02 '12 at 18:17

H H

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dang you beat me by a few seconds! – MattDavey Feb 02 '12 at 18:19
Dont think its an LOL situation - legit question... plus, will help new comers and others who weren't aware. After all, this is what the site is for. – bbqchickenrobot Feb 02 '12 at 18:22

score 5 · Answer 2 · answered Feb 02 '12 at 18:19

5

var arrayA = new [] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

var arrayB = new [] { 1, 2, 3, 7, 8 };

var result = arrayA.Except(arrayB);

answered Feb 02 '12 at 18:19

MattDavey

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score 1 · Answer 3 · answered Feb 02 '12 at 18:21

public void Linq52() 
{ 
    int[] numbersA = { 0, 2, 4, 5, 6, 8, 9 }; 
    int[] numbersB = { 1, 3, 5, 7, 8 }; 

    IEnumerable<int> aOnlyNumbers = numbersA.Except(numbersB); 

    Console.WriteLine("Numbers in first array but not second array:"); 
    foreach (var n in aOnlyNumbers) 
    { 
        Console.WriteLine(n); 
    } 
}

Find the number that don't exist in another array

3 Answers3