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Queryable.ElementAt(Of TSource) Method

Returns the element at a specified index in a sequence.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

'Declaration
<ExtensionAttribute> _
Public Shared Function ElementAt(Of TSource) ( _
	source As IQueryable(Of TSource), _
	index As Integer _
) As TSource

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Linq.IQueryable(Of TSource)
An IQueryable(Of T) to return an element from.
index
Type: System.Int32
The zero-based index of the element to retrieve.

Return Value

Type: TSource
The element at the specified position in source.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable(Of TSource). When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

ExceptionCondition
ArgumentNullException

source is Nothing.

ArgumentOutOfRangeException

index is less than zero.

The ElementAt(Of TSource)(IQueryable(Of TSource), Int32) method generates a MethodCallExpression that represents calling ElementAt(Of TSource)(IQueryable(Of TSource), Int32) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute(Of TResult)(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

The query behavior that occurs as a result of executing an expression tree that represents calling ElementAt(Of TSource)(IQueryable(Of TSource), Int32) depends on the implementation of the type of the source parameter. The expected behavior is that it returns the item at position index in source.

The following code example demonstrates how to use ElementAt(Of TSource)(IQueryable(Of TSource), Int32) to return an element at a specific position in a sequence.


        Dim names() As String = {"Hartono, Tommy", "Adams, Terry", _
                           "Andersen, Henriette Thaulow", _
                           "Hedlund, Magnus", "Ito, Shu"}

        Dim rand As New Random(DateTime.Now.Millisecond)

        Dim name As String = _
            names.AsQueryable().ElementAt(rand.Next(0, names.Length))

        MsgBox(String.Format("The name chosen at random is '{0}'.", name))

        ' This code produces the following sample output.
        ' Yours may be different due to the use of Random.
        '
        ' The name chosen at random is 'Ito, Shu'.



.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

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