Dictionary with integer array as a key

Question

I need a Dictionary whose key is an array of integers for example Dictionary or

Dictionary,string>.
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Answer 1

Instead of creating your own type, you could provide two methods somewhere

string ConvertListToString(List<int> l){...};
List<int> ConvertStringToList(string s){...};

and use a Dictionary<string,string> instead.

Answer 2

GetHashCode and Equality are defined for List, they're just not overridden to give you behavior that you might expect and instead.

If you're using .NET 3.5 you can write a extension methods for List that implements an override for both GetHashCode(), and Equality()

Answer 3

It isn't predefined because it is expensive. If you know your list is short then just implement the obvious overrides. If not, you'll have to come up with some kind of heuristic for at least GetHashCode. Say, GetHashCode of only the first couple of elements xor-ed together with the Length.