# HashSet<T>.CountHashSet<T>.CountHashSet<T>.CountHashSet<T>.Count Property

## Definition

Gets the number of elements that are contained in a set.

``````public:
property int Count { int get(); };``````
``public int Count { get; }``
``member this.Count : int``
``Public ReadOnly Property Count As Integer``
Property Value

The number of elements that are contained in the set.

Implements

## Examples

The following example demonstrates how to create, populate, and manipulate two HashSet<T> objects. In this example, both the contents of the set and Count display to the console.

``````using System;
using System.Collections.Generic;

class Program
{
static void Main()
{
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.

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

Console.Write("evenNumbers contains {0} elements: ", evenNumbers.Count);
DisplaySet(evenNumbers);

Console.Write("oddNumbers contains {0} elements: ", oddNumbers.Count);
DisplaySet(oddNumbers);

// Create a new HashSet populated with even numbers.
HashSet<int> numbers = new HashSet<int>(evenNumbers);
Console.WriteLine("numbers UnionWith oddNumbers...");
numbers.UnionWith(oddNumbers);

Console.Write("numbers contains {0} elements: ", numbers.Count);
DisplaySet(numbers);

}

private static void DisplaySet(HashSet<int> set)
{
Console.Write("{");
foreach (int i in set)
{
Console.Write(" {0}", i);
}
Console.WriteLine(" }");
}
}
/* This example produces output similar to the following:
* evenNumbers contains 5 elements: { 0 2 4 6 8 }
* oddNumbers contains 5 elements: { 1 3 5 7 9 }
* numbers UnionWith oddNumbers...
* numbers contains 10 elements: { 0 2 4 6 8 1 3 5 7 9 }
*/
``````
``````Imports System
Imports System.Collections.Generic

Class Program

Shared Sub Main()

Dim evenNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()
Dim oddNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()

For i As Integer = 0 To 4

' Populate evenNumbers with only even numbers.

' Populate oddNumbers with only odd numbers.
oddNumbers.Add((i * 2) + 1)
Next i

Console.Write("evenNumbers contains {0} elements: ", evenNumbers.Count)
DisplaySet(evenNumbers)

Console.Write("oddNumbers contains {0} elements: ", oddNumbers.Count)
DisplaySet(oddNumbers)

' Create a new HashSet populated with even numbers.
Dim numbers As HashSet(Of Integer) = New HashSet(Of Integer)(evenNumbers)
Console.WriteLine("numbers UnionWith oddNumbers...")
numbers.UnionWith(oddNumbers)

Console.Write("numbers contains {0} elements: ", numbers.Count)
DisplaySet(numbers)
End Sub

Private Shared Sub DisplaySet(ByVal coll As HashSet(Of Integer))
Console.Write("{")
For Each i As Integer In coll
Console.Write(" {0}", i)
Next i
Console.WriteLine(" }")
End Sub

End Class
' This example produces output similar to the following:
' evenNumbers contains 5 elements: { 0 2 4 6 8 }
' oddNumbers contains 5 elements: { 1 3 5 7 9 }
' numbers UnionWith oddNumbers...
' numbers contains 10 elements: { 0 2 4 6 8 1 3 5 7 9 }
``````

## Remarks

The capacity of a HashSet<T> object is the number of elements that the object can hold. A HashSet<T> object's capacity automatically increases as elements are added to the object.

The capacity is always greater than or equal to Count. If Count exceeds the capacity while adding elements, the capacity is set to the first prime number that is greater than double the previous capacity.

Retrieving the value of this property is an O(1) operation.