Enumerable.LastOrDefault(Of TSource) Method (IEnumerable(Of TSource), Func(Of TSource, Boolean))

.NET Framework (current version)

Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.

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

Syntax

<ExtensionAttribute>
Public Shared Function LastOrDefault(Of TSource) (
	source As IEnumerable(Of TSource),
	predicate As Func(Of TSource, Boolean)
) As TSource

Parameters

source: Type: System.Collections.Generic.IEnumerable(Of TSource)
An IEnumerable(Of T) to return an element from.

predicate: Type: System.Func(Of TSource, Boolean)
A function to test each element for a condition.

Return Value

Type: TSource

default(TSource) if the sequence is empty or if no elements pass the test in the predicate function; otherwise, the last element that passes the test in the predicate function.

Type Parameters

TSource: The type of the elements of source.

Exceptions

Exception	Condition
ArgumentNullException	source or predicate is null.

Remarks

The default value for reference and nullable types is null.

The following code example demonstrates how to use LastOrDefault(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Boolean)) by passing in a predicate. In the second call to the method, there is no element in the sequence that satisfies the condition.

' Create an array of doubles.
Dim numbers() As Double = {49.6, 52.3, 51.0, 49.4, 50.2, 48.3}

' Get the last item whose value rounds to 50.0.
Dim number50 As Double =
numbers.LastOrDefault(Function(n) Math.Round(n) = 50.0)

Dim output As New System.Text.StringBuilder
output.AppendLine("The last number that rounds to 50 is " & number50)

' Get the last item whose value rounds to 40.0.
Dim number40 As Double =
numbers.LastOrDefault(Function(n) Math.Round(n) = 40.0)

Dim text As String = IIf(number40 = 0.0,
                     "[DOES NOT EXIST]",
                     number40.ToString())
output.AppendLine("The last number that rounds to 40 is " & text)

' Display the output.
MsgBox(output.ToString)

' This code produces the following output:
'
' The last number that rounds to 50 is 50.2
' The last number that rounds to 40 is [DOES NOT EXIST]

Version Information

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