Getting unique items from a list [duplicate]

Question

What is the fastest / most efficient way of getting all the distinct items from a list?

I have a List<string> that possibly has multiple repeating items in it and only want the unique values within the list.

Answer 1

You can use the Distinct method to return an IEnumerable<T> of distinct items:

var uniqueItems = yourList.Distinct(); 

And if you need the sequence of unique items returned as a List<T>, you can add a call to ToList:

var uniqueItemsList = yourList.Distinct().ToList(); 

Answer 2

Use a HashSet<T>. For example:

var items = "A B A D A C".Split(' '); var unique_items = new HashSet<string>(items); foreach (string s in unique_items)     Console.WriteLine(s); 

prints

 A B D C