Enumerable.ElementAtOrDefault<TSource>(IEnumerable<TSource>, Int32) Method

Definition

Namespace:
System.Linq
Assembly:
System.Linq.dll
Assembly:
System.Core.dll
Assembly:
netstandard.dll

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

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static TSource ElementAtOrDefault(System::Collections::Generic::IEnumerable<TSource> ^ source, int index);
public static TSource ElementAtOrDefault<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, int index);
public static TSource? ElementAtOrDefault<TSource> (this System.Collections.Generic.IEnumerable<TSource> source, int index);
static member ElementAtOrDefault : seq<'Source> * int -> 'Source
<Extension()>
Public Function ElementAtOrDefault(Of TSource) (source As IEnumerable(Of TSource), index As Integer) As TSource

Type Parameters

TSource

The type of the elements of source.

Parameters

source
IEnumerable<TSource>

An IEnumerable<T> to return an element from.

index
Int32

The zero-based index of the element to retrieve.

Returns

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.

Exceptions

ArgumentNullException

source is null.

Examples

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

string[] names =
    { "Hartono, Tommy", "Adams, Terry", "Andersen, Henriette Thaulow",
        "Hedlund, Magnus", "Ito, Shu" };

int index = 20;

string name = names.ElementAtOrDefault(index);

Console.WriteLine(
    "The name chosen at index {0} is '{1}'.",
    index,
    String.IsNullOrEmpty(name) ? "<no name at this index>" : name);

/*
 This code produces the following output:

 The name chosen at index 20 is '<no name at this index>'.
*/

' 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.
Console.WriteLine($"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]

Remarks

If the type of source implements IList<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.

Applies to