CODEWITHSUNDEEP
c#.netvb.netdictionary
Elmo
Elmo

Reputation: 6471

Get all keys in Dictionary containing value x

I have this:

Dictionary<integer, string> dict = new Dictionary<integer, string>();

I want to select all the items in the dictionary that contain the value abc.

Is there an inbuilt function that lets me do this easily?

Upvotes: 20

Views: 37601

Answers (2)

Leonardo
Leonardo

Reputation: 11387

Built-in function? No sorry... but another (not so beautiful) way is to iterate using foreach(KeyValuePair<integer, string> ...

Upvotes: 0

Jon Skeet
Jon Skeet

Reputation: 1499840

Well it's reasonably simple with LINQ:

var matches = dict.Where(pair => pair.Value == "abc")
                  .Select(pair => pair.Key);

Note that this won't be even slightly efficient - it's an O(N) operation, as it needs to check every entry.

If you need to do this frequently, you may want to consider using another data structure - Dictionary<,> is specifically designed for fast lookups by key.

Upvotes: 55

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