Create copy of a HashSet in C#

This post will discuss how to create a copy of a HashSet<T> in C#.

The HashSet<T> class provides a Constructor that takes a collection and initializes a new instance of the HashSet<T> class with the elements copied from the specified collection. The following example demonstrate creating a new HashSet<T> instance from an existing Set.

using System;

using System.Collections.Generic;

public class Example

{

public static void Main()

{

HashSet<int> numbers = new HashSet<int>() { 1, 2, 3, 4, 5 };

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

Console.WriteLine(String.Join(", ", clone)); // 1, 2, 3, 4, 5

}

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You can also create a ToHashSet extension method to create a copy of a HashSet<T> is using its constructor, as shown below:

using System;

using System.Collections.Generic;

public static class Extensions

{

public static HashSet<T> ToHashSet<T>(this IEnumerable<T> source)

{

return new HashSet<T>(source);

}

public class Example

{

public static void Main()

{

HashSet<int> numbers = new HashSet<int>() { 1, 2, 3, 4, 5 };

HashSet<int> clone = numbers.ToHashSet();

Console.WriteLine(String.Join(", ", clone)); // 1, 2, 3, 4, 5

}

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The HashSet<T> class provides has another overload that ensures the same equality comparer is used as the original Set. For example, the following code uses a supplied comparer to allow case-insensitive comparisons on the elements of a HashSet<T> collection.

using System;

using System.Collections.Generic;

public static class Extensions

{

public static HashSet<T> ToHashSet<T>(this HashSet<T> source)

{

return new HashSet<T>(source, source.Comparer);

}

public class Example

{

public static void Main()

{

HashSet<string> numbers = new HashSet<string>(StringComparer.OrdinalIgnoreCase) {

"A", "a", "B", "C"

};

HashSet<string> clone = numbers.ToHashSet();

Console.WriteLine(String.Join(", ", clone)); // A, B, C

}

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That’s all about creating a copy of a HashSet<T> in C#.

Create copy of a HashSet in C#

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