Question

How do I get a Dictionary key by value in C#?

Dictionary<string, string> types = new Dictionary<string, string>()
{
    {"1", "one"},
    {"2", "two"},
    {"3", "three"}
};

I want something like this:

getByValueKey(string value);

getByValueKey("one") must be return "1".

What is the best way do this? Maybe HashTable or SortedLists?

Answer 1

Values do not necessarily have to be unique, so you have to do a lookup. You can do something like this:

var myKey = types.FirstOrDefault(x => x.Value == "one").Key;

If values are unique and are inserted less frequently than read, then create an inverse dictionary where values are keys and keys are values.