How is the hashset used in C#?

In C#, the HashSet is a collection class used to store unique elements. It is based on the data structure of a hash table and allows for efficient insertion, deletion, and search operations.

The main uses of a HashSet are as follows:

1. Instantiate a HashSet object.
2. Create a new HashSet object named set.
3. Add elements:
4. Add the item to the set.
5. Remove elements.
6. Remove the item from the set.
7. Determine if the element exists:
8. Does the set contain the item?
9. Get the number of elements in the collection.
10. There are a total of ‘count’ elements in the set.
11. Iterate through the elements in the collection.
12. for each element in the set, do something with it.
13. Merge two hash sets:
14. Combine the set with the otherSet.
15. Find the intersection of two HashSets.
16. Find the intersection between the two sets.
17. Find the difference between two HashSet.
18. Update the set by removing all elements that are also in the otherSet.

It is important to note that elements in a HashSet must be hashable, so it requires the element type T to implement the GetHashCode() and Equals() methods.

In addition, HashSet also offers other methods and properties that can be used according to specific needs.