HashSet<T>.ExceptWith Method

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

Namespace:  System.Collections.Generic
Assembly:  System.Core (in System.Core.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: 4.5.2, 4.5.1, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

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

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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