c# - Check if two list have the same items

Question

I have two lists as below, how can I say that they have the same elements. The order is not important.

var list1 = new List<int> {1,2,3};
var list2 = new List<int> {2,1,3};

How can I say that these are equal? Should I write my own method or is there a built-in method for it?

Answer 1

That's what sets (e.g., HashSet<T>) are for. Sets have no defined order, and SetEquals verifies whether the set and another collection contain the same elements.

var set = new HashSet<int>(list1);
var equals = set.SetEquals(list2);