Linq, determine if list are equals

Question

How to determine, if items in a List<List<int>> are equals ?

List<List<int>> equals = new List<List<int>>()
{
    new List<int>() { 1,2 },
    new List<int>() { 1,2 }
};

List<List<int>> notEquals = new List<List<int>>()
{
    new List<int>() { 1,2 },
    new List<int>() { 2,500}
};

Are lists `{1, 2}` and `{2, 1}` equal or not? Does order matter? — Dmitry Bychenko, Dec 08 '15 at 11:42
@SergiiZhevzhyk . No duplicate. In my example, i have only 2 items, but eventually more — BobyOneKenobi, Dec 08 '15 at 12:21
@BobyOneKenobi: in that case the accepted Tim Schmelter's answer is *not* the one you're looking for: `SequenceEqual` *depends* on order. — Dmitry Bychenko, Dec 08 '15 at 12:32

score 5 · Accepted Answer · answered Dec 08 '15 at 11:44

5

You need to compare the first list with all others, you can use SequenceEqual:

List<int> first = yourLists[0];
bool allEqual = yourLists.Skip(1).All(l => first.SequenceEqual(l));

Since All returns false on the first unequal list this is pretty efficient.

answered Dec 08 '15 at 11:44

Tim Schmelter

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Good. But isn't this works? `bool allEqual = first.SequenceEqual(yourLists[1]);` – Salah Akbari Dec 08 '15 at 11:50
@user2946329: if the list can only contain two sub-lists that works too. But my approach works even if it contains more than two. You are comparing only the first with the second list. What if there's a third list which is unequal? – Tim Schmelter Dec 08 '15 at 11:51
Right. So your answer is more comprehensive. – Salah Akbari Dec 08 '15 at 11:55

Linq, determine if list are equals

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