HashSet<T>.Add(T) HashSet<T>.Add(T) HashSet<T>.Add(T) HashSet<T>.Add(T) Method

Definition

Adds the specified element to a set.

public:
 virtual bool Add(T item);
public bool Add (T item);
abstract member Add : 'T -> bool
override this.Add : 'T -> bool
Public Function Add (item As T) As Boolean
Parameters
item
T T T T

The element to add to the set.

Returns

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

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);
}

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