LastOrDefault(TSource) Method (IEnumerable(TSource), Func(TSource, Boolean))

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

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)

'Declaration
<ExtensionAttribute> _
Public Shared Function LastOrDefault(Of TSource) ( _
	source As IEnumerable(Of TSource), _
	predicate As Func(Of TSource, Boolean) _
) As TSource
'Usage
Dim source As IEnumerable(Of TSource)
Dim predicate As Func(Of TSource, Boolean)
Dim returnValue As TSource

returnValue = source.LastOrDefault(predicate)

Type Parameters

TSource

The type of the elements of source.

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.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of 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).

ExceptionCondition
ArgumentNullException

source or predicate is Nothing.

The default value for reference and nullable types is Nothing.

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]

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5

.NET Compact Framework

Supported in: 3.5

XNA Framework

Supported in: 3.0

Community Additions

ADD
Show:
© 2016 Microsoft