What are some examples of using HashSet in C#?

What are some examples of using HashSet in C#?

HashSet in C# is a collection that contains no duplicate elements. 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(3);
   

3. Checking for existence:

   bool exists = 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! Here are some common set operations you can perform with HashSet:

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:

   setA.IntersectWith(setB); // setA now contains { 3 }
   

3. Difference:

   setA.ExceptWith(setB); // setA now contains { 1, 2 }
   

4. Symmetric Difference:

   setA.SymmetricExceptWith(setB); // setA now contains { 1, 2, 4, 5 }
   

These operations allow you to manipulate sets effectively. Do you have any specific scenarios in mind?

Can you explain the performance benefits of using HashSet?

Absolutely! The performance benefits of using HashSet include:

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, ensuring that each element is unique without additional checks.
3. Dynamic Sizing: HashSet can grow dynamically as you add elements, which means you don't have to worry about the initial size.
4. Set Operations: Built-in methods for union, intersection, and difference are optimized for performance.

These features make HashSet a great choice for scenarios where you need fast access and uniqueness. Would you like to know more about its limitations?