What are some examples of using HashSet in C#?

What are some examples of using HashSet in C#?

In C#, a HashSet is a collection that contains no duplicate elements and is not sorted. Here are a few examples:

1. Creating a HashSet:

   HashSet<int> numbers = new HashSet<int>();
   

2. Adding elements:

   numbers.Add(1);
   numbers.Add(2);
   numbers.Add(2); // This will not be added again
   

3. Checking for existence:

   bool hasTwo = numbers.Contains(2); // returns true
   

4. Removing elements:

   numbers.Remove(1);
   

5. Iterating through a HashSet:

   foreach (var number in numbers) {
       Console.WriteLine(number);
   }
   

Would you like to see more advanced examples?

Yes, can you show me how to perform set operations with HashSet?

Certainly! HashSet supports several set operations like union, intersection, and difference. Here are examples:

1. Union:

   HashSet<int> setA = new HashSet<int> { 1, 2, 3 };
   HashSet<int> setB = new HashSet<int> { 3, 4, 5 };
   setA.UnionWith(setB); // setA now contains 1, 2, 3, 4, 5
   

2. Intersection:

   HashSet<int> intersection = new HashSet<int>(setA);
   intersection.IntersectWith(setB); // intersection now contains 3
   

3. Difference:

   HashSet<int> difference = new HashSet<int>(setA);
   difference.ExceptWith(setB); // difference now contains 1, 2
   

These operations are very efficient with HashSet. Do you need help with anything else?

What are the performance benefits of using HashSet?

HashSet offers several performance benefits:

1. Fast Lookups: HashSet provides average O(1) time complexity for lookups, making it very efficient for checking if an item exists.
2. No Duplicates: It automatically handles duplicates, so you don't have to check for them manually.
3. Dynamic Sizing: HashSet can grow dynamically as you add more elements, which is more efficient than arrays in terms of memory management.

These features make HashSet a great choice for scenarios where you need to manage a collection of unique items efficiently.