HashSet<T>.Add(T) Method

Reference

Definition

Namespace:: System.Collections.Generic

Assembly:: System.Collections.dll

Assembly:: System.Core.dll

Assembly:: netstandard.dll

Source:: HashSet.cs

Source:: HashSet.cs

Source:: HashSet.cs

Important

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Adds the specified element to a set.

public:
 virtual bool Add(T item);

public:
 bool Add(T item);

public bool Add (T item);

abstract member Add : 'T -> bool
override this.Add : 'T -> bool

member this.Add : 'T -> bool

Public Function Add (item As T) As Boolean

Parameters

item: T

The element to add to the set.

Returns

Boolean

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

Implements

Add(T)

Examples

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);
}

let evenNumbers = HashSet<int>()
let oddNumbers = HashSet<int>()

for i = 0 to 4 do
    // Populate numbers with just even numbers.
    evenNumbers.Add(i * 2) |> ignore

    // Populate oddNumbers with just odd numbers.
    oddNumbers.Add(i * 2 + 1) |> ignore

Remarks

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.

Applies to

Jaa