HashSet<T>.ExceptWith Method

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

Namespace:  System.Collections.Generic
Assemblies:   System.Core (in System.Core.dll)
  System.Collections (in System.Collections.dll)

public void ExceptWith(
	IEnumerable<T> other
)

Parameters

other
Type: System.Collections.Generic.IEnumerable<T>

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

Implements

ISet<T>.ExceptWith(IEnumerable<T>)

ExceptionCondition
ArgumentNullException

other is null.

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.

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.

static void Main()
{
    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);



}
/* 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 }
 */

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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