Question

I am trying to filter an IEnumerable object of the duplicate values, so I would like to get the distinct values from it, for example, lets say that it holds days:

monday tuesday wednesday wednesday

I would like to filter it and return:

monday tuesday wednesday

What is the most efficient way to do this in .net 2.0?

Answer 1

Dictionary<object, object> list = new Dictionary<object, object>(); foreach (object o in enumerable)     if (!list.ContainsKey(o))     {         // Do the actual work.         list[o] = null;     } 

Dictionary will use a hash table to hold keys therefore lookup is efficient.

Sorting will be O(n log(n)) at best. A hash table with an efficient hash function often outperforms it (O(1) lookups).