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.NET Framework Class Library

Enumerable.LastOrDefault<TSource> Method (IEnumerable<TSource>)

Returns the last element of a sequence, or a default value if the sequence contains no elements.

Namespace:  System.Linq
Assemblies:   System.Linq (in System.Linq.dll)
  System.Core (in System.Core.dll)
<ExtensionAttribute> _
Public Shared Function LastOrDefault(Of TSource) ( _
	source As IEnumerable(Of TSource) _
) As TSource

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>

An IEnumerable<T> to return the last element of.

Return Value

Type: TSource
default(TSource) if the source sequence is empty; otherwise, the last element in the IEnumerable<T>.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<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).
Exception Condition
ArgumentNullException

source is null.

The default value for reference and nullable types is null.

The LastOrDefault method does not provide a way to specify a default value. If you want to specify a default value other than default(TSource), use the DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource) method as described in the Example section.

The following code example demonstrates how to use LastOrDefault<TSource>(IEnumerable<TSource>) on an empty array.

        ' Create an empty array. 
        Dim fruits() As String = {}

        ' Get the last item in the array, or a 
        ' default value if there are no items. 
        Dim last As String = fruits.LastOrDefault()

        ' Display the result.
        MsgBox(IIf(String.IsNullOrEmpty(last), _
                   "<string is Nothing or empty>", _
                   last))

        ' This code produces the following output: 
        
        ' <string is Nothing or empty>

Sometimes the value of default(TSource) is not the default value that you want to use if the collection contains no elements. Instead of checking the result for the unwanted default value and then changing it if necessary, you can use the DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource) method to specify the default value that you want to use if the collection is empty. Then, call Last<TSource>(IEnumerable<TSource>) to obtain the last element. The following code example uses both techniques to obtain a default value of 1 if a collection of numeric days of the month is empty. Because the default value for an integer is 0, which does not correspond to any day of the month, the default value must be specified as 1 instead. The first result variable is checked for the unwanted default value after the query has finished executing. The second result variable is obtained by using DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource) to specify a default value of 1.

        Dim daysOfMonth As New List(Of Integer)(New Integer() {})

        ' Setting the default value to 1 after the query. 
        Dim lastDay1 As Integer = daysOfMonth.LastOrDefault()
        If lastDay1 = 0 Then
            lastDay1 = 1
        End If
        MsgBox(String.Format("The value of the lastDay1 variable is {0}", lastDay1))

        ' Setting the default value to 1 by using DefaultIfEmpty() in the query. 
        Dim lastDay2 As Integer = daysOfMonth.DefaultIfEmpty(1).Last()
        MsgBox(String.Format("The value of the lastDay2 variable is {0}", lastDay2))

        ' This code produces the following output: 
        
        ' The value of the lastDay1 variable is 1 
        ' The value of the lastDay2 variable is 1

.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

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library