HashSet<T>.ExceptWith(IEnumerable<T>) Method

Definition

Namespace:

System.Collections.Generic

Assemblies:

netstandard.dll, System.Collections.dll

Source:

HashSet.cs

Removes all elements in the specified collection from the current HashSet<T> object.

C#

public void ExceptWith(System.Collections.Generic.IEnumerable<T> other);

Parameters

other

IEnumerable<T>

The collection of items to remove from the HashSet<T> object.

Implements

ExceptWith(IEnumerable<T>)

Exceptions

ArgumentNullException

other is null.

Examples

The following example creates two HashSet<T> collections with overlapping sets of data. The lower range of values is then removed from the larger set using the ExceptWith method.

C#

HashSet<int> lowNumbers = new HashSet<int>();
HashSet<int> highNumbers = new HashSet<int>();

for (int i = 0; i < 6; i++)
{
    lowNumbers.Add(i);
}

for (int i = 3; i < 10; i++)
{
    highNumbers.Add(i);
}

Console.Write("lowNumbers contains {0} elements: ", lowNumbers.Count);
DisplaySet(lowNumbers);

Console.Write("highNumbers contains {0} elements: ", highNumbers.Count);
DisplaySet(highNumbers);

Console.WriteLine("highNumbers ExceptWith lowNumbers...");
highNumbers.ExceptWith(lowNumbers);

Console.Write("highNumbers contains {0} elements: ", highNumbers.Count);
DisplaySet(highNumbers);

void DisplaySet(HashSet<int> set)
{
    Console.Write("{");
    foreach (int i in set)
    {
        Console.Write(" {0}", i);
    }
    Console.WriteLine(" }");
}

/* This example provides output similar to the following:
* lowNumbers contains 6 elements: { 0 1 2 3 4 5 }
* highNumbers contains 7 elements: { 3 4 5 6 7 8 9 }
* highNumbers ExceptWith lowNumbers...
* highNumbers contains 4 elements: { 6 7 8 9 }
*/

Remarks

The ExceptWith method is the equivalent of mathematical set subtraction.

This method is an O(n) operation, where n is the number of elements in the other parameter.

Applies to