Getting common values in two array issue using LINQ

Question

I have two arrays say

var list1 = string[] {"1", "2", "3", "4", "", ""};
var list2 = string[] {"2", "3", "4","",""};

When i try to get common items form these two array using following code

 var listCommon = list1.Intersect(list2);

It gives me result like this

string[] {"2", "3", "4", ""}

But i want it should return like this

string[] {"2", "3", "4", "", ""}

It is escaping last empty string value while intersecting.

Answer 1

Set methods like Intersect or Except remove duplicates from each collection. I assume you want something like this instead:

var listCommon = list1.Where(list2.Contains);

which is not as efficient. This could be an optimization:

var l2Lookup = new HashSet<string>(list2);
var listCommon = list1.Where(l2Lookup.Contains);

Answer 2

This will work:

list1.Where(x=>list2.Contains(x))