Enumerable.ElementAtOrDefault(Of TSource) Method (IEnumerable(Of TSource), Int32)

 

Returns the element at a specified index in a sequence or a default value if the index is out of range.

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

<ExtensionAttribute>
Public Shared Function ElementAtOrDefault(Of TSource) (
	source As IEnumerable(Of TSource),
	index As Integer
) As TSource

Parameters

source
Type: System.Collections.Generic.IEnumerable(Of TSource)

An IEnumerable(Of T) to return an element from.

index
Type: System.Int32

The zero-based index of the element to retrieve.

Return Value

Type: TSource

default(TSource) if the index is outside the bounds of the source sequence; otherwise, the element at the specified position in the source sequence.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source is null.

If the type of source implements IList(Of T), that implementation is used to obtain the element at the specified index. Otherwise, this method obtains the specified element.

The default value for reference and nullable types is null.

The following code example demonstrates how to use ElementAtOrDefault(Of TSource). This example uses an index that is outside the bounds of the array.

' Create an array of strings.
Dim names() As String = _
    {"Hartono, Tommy", "Adams, Terry", "Andersen, Henriette Thaulow", "Hedlund, Magnus", "Ito, Shu"}

Dim index As Integer = 20

' Get a string at an index that is out of range in the array.
Dim name As String = names.ElementAtOrDefault(index)

Dim text As String = If(String.IsNullOrEmpty(name), "[THERE IS NO NAME AT THIS INDEX]", name)

' Display the output.
MsgBox("The name chosen at index " & index & " is " & text)

' This code produces the following output:
'
' The name chosen at index 20 is [THERE IS NO NAME AT THIS INDEX]

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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