HashSet(Of T).UnionWith Method (IEnumerable(Of T))

 

Modifies the current HashSet(Of T) object to contain all elements that are present in itself, the specified collection, or both.

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

Public Sub UnionWith (
	other As IEnumerable(Of T)
)

Parameters

other
Type: System.Collections.Generic.IEnumerable(Of T)

The collection to compare to the current HashSet(Of T) object.

Exception Condition
ArgumentNullException

other is null.

This method is an O(n) operation, where n is the number of elements in the other parameter.

The following example demonstrates how to merge two disparate sets. This example creates two HashSet(Of T) objects, and populates them with even and odd numbers, respectively. A third HashSet(Of T) object is created from the set that contains the even numbers. The example then calls the UnionWith method, which adds the odd number set to the third set.

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.
            evenNumbers.Add(i * 2)

            ' 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 }

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 4.0
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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