Question

Possible Duplicate:
Bidirectional 1 to 1 Dictionary in C#

Im curious if a datastructure exists in the standard .net libraries that can represent a 1-1 relationship, such as the following

1-a
4-b
6-c
5-d

Where I can say:

thisstructure[1] // returns "a"
thisstructure.GetKey["d"] // return 5

I understand all keys would have to be unique, does anything similar exist?

Thanks!

Answer 1

Could this method fit your needs?

public static class Extensions
{
    public static TKey GetKey<TKey, TValue>(this Dictionary<TKey, TValue> dict, TValue value)
    {
        int index = dict.Values.ToList().IndexOf(value);

        if (index == -1)
        {
            return default(TKey); //or maybe throw an exception
        }

        return dict.Keys.ToList()[index];
    }
}

You could then use it like so:

Dictionary<int, char> dict = new Dictionary<int, char>();
dict.Add(1, 'a');
dict.Add(4, 'b');
dict.Add(6, 'c');
dict.Add(5, 'd');

Console.WriteLine(dict.GetKey('d')); //5