Question

I need a C# method to remove duplicates from a List<T> using a custom comparison operation. In .NET 4. Is there one or do I have to write it myself?

Answer 1

Assuming your comparison operation is IEqualityComparer<T> or can be converted to it, you’re fine with LINQ:

var newList = oldList.Distinct(customComparer).ToList();

Obviously that creates a new list rather than removing elements from the old one, but in most cases that’s okay. You could always completely replace the contents of the old list with the new list afterwards if not…