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.NET Development
.NET Framework 3.5
HashSet(T) Class
 Overlaps Method

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Microsoft Visual Studio 2008/.NET Framework 3.5

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.NET Framework Class Library
HashSet<(Of <(T>)>)..::.Overlaps Method

Determines whether the current HashSet<(Of <(T>)>) object overlaps the specified collection.

Namespace:  System.Collections.Generic
Assembly:  System.Core (in System.Core.dll)
Visual Basic (Declaration)
Public Function Overlaps ( _
    other As IEnumerable(Of T) _
) As Boolean
Visual Basic (Usage)
Dim instance As HashSet
Dim other As IEnumerable(Of T)
Dim returnValue As Boolean

returnValue = instance.Overlaps(other)
C#
public bool Overlaps(
    IEnumerable<T> other
)
Visual C++
public:
bool Overlaps(
    IEnumerable<T>^ other
)
JScript
public function Overlaps(
    other : IEnumerable<T>
) : boolean

Parameters

other
Type: System.Collections.Generic..::.IEnumerable<(Of <(T>)>)
The collection to compare to the current HashSet<(Of <(T>)>) object.

Return Value

Type: System..::.Boolean
true if the HashSet<(Of <(T>)>) object and other share at least one common element; otherwise, false.
ExceptionCondition
ArgumentNullException

other is nullNothingnullptra null reference (Nothing in Visual Basic).

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

The following example creates two disparate HashSet<(Of <(T>)>) objects and compares them to each another. In this example, allNumbers and lowNumbers are shown to share common elements using the Overlaps method.

Visual Basic
Shared Sub Main()

    Dim lowNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()
    Dim allNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()

    For i As Integer = 1 To 4
        lowNumbers.Add(i)
    Next i

    For i As Integer = 0 To 9
        allNumbers.Add(i)
    Next i


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

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

    Console.WriteLine("lowNumbers overlaps allNumbers: {0}", _
        lowNumbers.Overlaps(allNumbers))

    Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}", _
        allNumbers.SetEquals(lowNumbers))

    ' Show the results of sub/superset testing
    Console.WriteLine("lowNumbers is a subset of allNumbers: {0}", _
        lowNumbers.IsSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a superset of lowNumbers: {0}", _
        allNumbers.IsSupersetOf(lowNumbers))
    Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}", _
        lowNumbers.IsProperSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}", _
        allNumbers.IsProperSupersetOf(lowNumbers))

    ' Modify allNumbers to remove numbers that are not in lowNumbers.
    allNumbers.IntersectWith(lowNumbers)
    Console.Write("allNumbers contains {0} elements: ", allNumbers.Count)
    DisplaySet(allNumbers)

    Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}", _
        allNumbers.SetEquals(lowNumbers))

    ' Show the results of sub/superset testing with the modified set.
    Console.WriteLine("lowNumbers is a subset of allNumbers: {0}", _
        lowNumbers.IsSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a superset of lowNumbers: {0}", _
        allNumbers.IsSupersetOf(lowNumbers))
    Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}", _
        lowNumbers.IsProperSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}", _
        allNumbers.IsProperSupersetOf(lowNumbers))
End Sub
' This code example produces output similar to the following:
' lowNumbers contains 4 elements: { 1 2 3 4 }
' allNumbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
' lowNumbers overlaps allNumbers: True
' allNumbers and lowNumbers are equal sets: False
' lowNumbers is a subset of allNumbers: True
' allNumbers is a superset of lowNumbers: True
' lowNumbers is a proper subset of allNumbers: True
' allNumbers is a proper superset of lowNumbers: True
' allNumbers contains 4 elements: { 1 2 3 4 }
' allNumbers and lowNumbers are equal sets: True
' lowNumbers is a subset of allNumbers: True
' allNumbers is a superset of lowNumbers: True
' lowNumbers is a proper subset of allNumbers: False
' allNumbers is a proper superset of lowNumbers: False

C#
static void Main()
{
    HashSet<int> lowNumbers = new HashSet<int>();
    HashSet<int> allNumbers = new HashSet<int>();

    for (int i = 1; i < 5; i++)
    {
        lowNumbers.Add(i);
    }

    for (int i = 0; i < 10; i++)
    {
        allNumbers.Add(i);
    }

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

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

    Console.WriteLine("lowNumbers overlaps allNumbers: {0}",
        lowNumbers.Overlaps(allNumbers));

    Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}",
        allNumbers.SetEquals(lowNumbers));

    // Show the results of sub/superset testing
    Console.WriteLine("lowNumbers is a subset of allNumbers: {0}",
        lowNumbers.IsSubsetOf(allNumbers));
    Console.WriteLine("allNumbers is a superset of lowNumbers: {0}",
        allNumbers.IsSupersetOf(lowNumbers));
    Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}",
        lowNumbers.IsProperSubsetOf(allNumbers));
    Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}",
        allNumbers.IsProperSupersetOf(lowNumbers));

    // Modify allNumbers to remove numbers that are not in lowNumbers.
    allNumbers.IntersectWith(lowNumbers);
    Console.Write("allNumbers contains {0} elements: ", allNumbers.Count);
    DisplaySet(allNumbers);

    Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}",
        allNumbers.SetEquals(lowNumbers));

    // Show the results of sub/superset testing with the modified set.
    Console.WriteLine("lowNumbers is a subset of allNumbers: {0}",
        lowNumbers.IsSubsetOf(allNumbers));
    Console.WriteLine("allNumbers is a superset of lowNumbers: {0}",
        allNumbers.IsSupersetOf(lowNumbers));
    Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}",
        lowNumbers.IsProperSubsetOf(allNumbers));
    Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}",
        allNumbers.IsProperSupersetOf(lowNumbers));
}
/* This code example produces output similar to the following:
 * lowNumbers contains 4 elements: { 1 2 3 4 }
 * allNumbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
 * lowNumbers overlaps allNumbers: True
 * allNumbers and lowNumbers are equal sets: False
 * lowNumbers is a subset of allNumbers: True
 * allNumbers is a superset of lowNumbers: True
 * lowNumbers is a proper subset of allNumbers: True
 * allNumbers is a proper superset of lowNumbers: True
 * allNumbers contains 4 elements: { 1 2 3 4 }
 * allNumbers and lowNumbers are equal sets: True
 * lowNumbers is a subset of allNumbers: True
 * allNumbers is a superset of lowNumbers: True
 * lowNumbers is a proper subset of allNumbers: False
 * allNumbers is a proper superset of lowNumbers: False
 */

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5
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