LINQ: Check whether Two List Are The Same

Question

This should be easy.

I want to check whether two list are the same in that they contain all the same elements or not, orders not important.

Duplicated elements are considered equal, i.e.e, new[]{1,2,2} is the same with new[]{2,1}

Answer 1

You need to get the intersection of the two lists:

bool areIntersected = t1.Intersect(t2).Count() > 0;

In response to you're modified question:

bool areSameIntersection = t1.Except(t2).Count() == 0 && t2.Except(t1).Count() == 0;

Answer 2

If the count of list1 elements in list2 equals the count of list2 elements in list1, then the lists both contain the same number of elements, are both subsets of each other - in other words, they both contain the same elements.

if (list1.Count(l => list2.Contains(l)) == list2.Count(l => list1.Contains(l)))
    return true;
else
    return false;

Answer 3

Edit: This was written before the OP added that { 1, 2, 2 } equals { 1, 1, 2 } (regarding handling of duplicate entries).

This will work as long as the elements are comparable for order.

bool equal = list1.OrderBy(x => x).SequenceEqual(list2.OrderBy(x => x));

Answer 4

var same = list1.Except(list2).Count() == 0 && 
           list2.Except(list1).Count() == 0;