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HashSet<T>.Add Method

Adds the specified element to a set.

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

public bool Add(
	T item
)

Parameters

item
Type: T
The element to add to the set.

Return Value

Type: System.Boolean
true if the element is added to the HashSet<T> object; false if the element is already present.

Implements

ISet<T>.Add(T)

If Count already equals the capacity of the HashSet<T> object, the capacity is automatically adjusted to accommodate the new item.

If Count is less than the capacity of the internal array, this method is an O(1) operation. If the HashSet<T> object must be resized, this method becomes an O(n) operation, where n is Count.

The following example demonstrates how to create and populate two HashSet<T> objects. This example is part of a larger example provided for the UnionWith method.


HashSet<int> evenNumbers = new HashSet<int>();
HashSet<int> oddNumbers = new HashSet<int>();

for (int i = 0; i < 5; i++)
{
    // Populate numbers with just even numbers.
    evenNumbers.Add(i * 2);

    // Populate oddNumbers with just odd numbers.
    oddNumbers.Add((i * 2) + 1);
}


.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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