C# HashSets

Introduction to HashSets

HashSet<T> in C# is a collection that stores unique elements, similar to a mathematical set. It does not maintain any particular order and can efficiently manage a large number of elements. HashSets are part of the System.Collections.Generic namespace.

Creating a HashSet

To create a HashSet, you can use the following syntax. Note that you need to specify the type of elements the HashSet will store:

Adding Elements to a HashSet

Use the Add method to insert elements into a HashSet. If an element already exists, it will not be added again, ensuring all elements are unique.

Removing Elements from a HashSet

Elements can be removed using the Remove method. If the element exists, it will be removed and the method will return true. If not, it will return false.

Iterating Over a HashSet

HashSets can be iterated using a foreach loop. This allows you to perform operations on each element.

Common HashSet Operations

HashSets support set operations such as union, intersection, and difference. These operations modify the set itself or return a new set.

Union of Two HashSets

The UnionWith method adds elements from another collection, excluding duplicates.

Intersection of Two HashSets

The IntersectWith method keeps only the elements that are present in both collections.

Difference of Two HashSets

The ExceptWith method removes elements present in another collection.

Conclusion

HashSets are a powerful tool in C# for storing unique elements and performing efficient set operations. They are particularly useful when you need to ensure that a collection contains no duplicate elements and when you want to perform operations such as union, intersection, or difference.