.NET Framework Class Library
EnumerableElementAtOrDefaultTSource Method

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)
Syntax
<[%$TOPIC/bb494386_en-us_VS_110_1_0_0_0_0%]> _
Public Shared Function ElementAtOrDefault(Of TSource) ( _
	source As [%$TOPIC/bb494386_en-us_VS_110_1_0_0_0_1%](Of TSource), _
	index As [%$TOPIC/bb494386_en-us_VS_110_1_0_0_0_2%] _
) As TSource
public static TSource ElementAtOrDefault<TSource>(
	this [%$TOPIC/bb494386_en-us_VS_110_1_0_1_0_0%]<TSource> source,
	[%$TOPIC/bb494386_en-us_VS_110_1_0_1_0_1%] index
)
[[%$TOPIC/bb494386_en-us_VS_110_1_0_2_0_0%]]
public:
generic<typename TSource>
static TSource ElementAtOrDefault(
	[%$TOPIC/bb494386_en-us_VS_110_1_0_2_0_1%]<TSource>^ source, 
	[%$TOPIC/bb494386_en-us_VS_110_1_0_2_0_2%] index
)
static member ElementAtOrDefault : 
        source:[%$TOPIC/bb494386_en-us_VS_110_1_0_3_0_0%]<'TSource> * 
        index:[%$TOPIC/bb494386_en-us_VS_110_1_0_3_0_1%] -> 'TSource 
JScript does not support generic types or methods.

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.GenericIEnumerableTSource

An IEnumerableT to return an element from.

index
Type: SystemInt32

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.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerableTSource. 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).
Exceptions
ExceptionCondition
ArgumentNullException

source is .

Remarks

If the type of source implements IListT, 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 .

Examples

The following code example demonstrates how to use ElementAtOrDefaultTSource. 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]
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>'.
            */
Version Information

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8