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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.

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 }
 */

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

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

.NET Framework

Supported in: 3.5
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