HashSet<T>.UnionWith(IEnumerable<T>) Method
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Modifies the current HashSet<T> object to contain all elements that are present in itself, the specified collection, or both.
public:
virtual void UnionWith(System::Collections::Generic::IEnumerable<T> ^ other);
public:
void UnionWith(System::Collections::Generic::IEnumerable<T> ^ other);
public void UnionWith (System.Collections.Generic.IEnumerable<T> other);
abstract member UnionWith : seq<'T> -> unit
override this.UnionWith : seq<'T> -> unit
member this.UnionWith : seq<'T> -> unit
Public Sub UnionWith (other As IEnumerable(Of T))
- other
- IEnumerable<T>
The collection to compare to the current HashSet<T> object.
other
is null
.
The following example demonstrates how to merge two disparate sets. This example creates two HashSet<T> objects, and populates them with even and odd numbers, respectively. A third HashSet<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.
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);
}
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);
void DisplaySet(HashSet<int> collection)
{
Console.Write("{");
foreach (int i in collection)
{
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 }
*/
let displaySet (collection: HashSet<int>) =
printf "{"
for i in collection do
printf $" {i}"
printfn " }"
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
printf $"evenNumbers contains {evenNumbers.Count} elements: "
displaySet evenNumbers
printf $"oddNumbers contains {oddNumbers.Count} elements: "
displaySet oddNumbers
// Create a new HashSet populated with even numbers.
let numbers = HashSet<int> evenNumbers
printfn "numbers UnionWith oddNumbers..."
numbers.UnionWith oddNumbers
printf $"numbers contains {numbers.Count} elements: "
displaySet numbers
// 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.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 collection As HashSet(Of Integer))
Console.Write("{")
For Each i As Integer In collection
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 }
This method is an O(n
) operation, where n
is the number of elements in the other
parameter.
Product | Versions |
---|---|
.NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
.NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
.NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
UWP | 10.0 |
.NET feedback
.NET is an open source project. Select a link to provide feedback: