Remove duplicates from a List in C#

Question

Anyone have a quick method for de-duplicating a generic List in C#?

Answer 1

As kronoz said in .Net 3.5 you can use Distinct().

In .Net 2 you could mimic it:

public IEnumerable DedupCollection (IEnumerable input) 
{
    var passedValues = new HashSet();

    // Relatively simple dupe check alg used as example
    foreach(T item in input)
        if(passedValues.Add(item)) // True if item is new
            yield return item;
}

This could be used to dedupe any collection and will return the values in the original order.

It's normally much quicker to filter a collection (as both Distinct() and this sample does) than it would be to remove items from it.