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

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