comparing two lists of string and if one of the item match do some processing

Question

I have two lists of string. I want to compare each elements in one list with another and if at least one of them match then do some processing else dont do anything.

I dont know how to do. I do have the following lists and the code I used was SequenceEqual but my lead said its wrong as it just compares if its equal or not and does nothing. I couldn't disagree and I want to achieve my intended functionality I mentioned above. Please help. As you seem, order doesn't matter, here 123 is in both list but in different order, so it matches and hence do some processing as per my requirement.

List<string> list1 = new List<string> () { "123", "234" };

List<string> list2 = new List<string> () { "333", "234" , "123"};

Answer 1

You can use Intersect to find common elements:

var intersecting = list1.Intersect(list2);

If you just want to know if there are common elements append .Any():

bool atLeastOneCommonElement = intersecting.Any();

If you want to process them:

foreach(var commonElement in intersecting)
{
    // do something ...
}