When should I use the HashSet type?

Question

I am exploring the HashSet type, but I don\'t understand where it stands in collections.

Can one use it to replace a List

Answer 1

In the basic intended scenario HashSet should be used when you want more specific set operations on two collections than LINQ provides. LINQ methods like Distinct, Union, Intersect and Except are enough in most situations, but sometimes you may need more fine-grained operations, and HashSet provides:

• UnionWith
• IntersectWith
• ExceptWith
• SymmetricExceptWith
• Overlaps
• IsSubsetOf
• IsProperSubsetOf
• IsSupersetOf
• IsProperSubsetOf
• SetEquals

Another difference between LINQ and HashSet "overlapping" methods is that LINQ always returns a new IEnumerable, and HashSet methods modify the source collection.