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Enumerable.Max(Of TSource, TResult) Method (IEnumerable(Of TSource), Func(Of TSource, TResult))

Invokes a transform function on each element of a generic sequence and returns the maximum resulting value.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)
'Declaration
<ExtensionAttribute> _
Public Shared Function Max(Of TSource, TResult) ( _
	source As IEnumerable(Of TSource), _
	selector As Func(Of TSource, TResult) _
) As TResult

Type Parameters

TSource

The type of the elements of source.

TResult

The type of the value returned by selector.

Parameters

source
Type: System.Collections.Generic.IEnumerable(Of TSource)

A sequence of values to determine the maximum value of.

selector
Type: System.Func(Of TSource, TResult)

A transform function to apply to each element.

Return Value

Type: TResult
The maximum value in the sequence.

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 selector is Nothing.

If type TResult implements IComparable(Of T), this method uses that implementation to compare values. Otherwise, if type TResult implements IComparable, that implementation is used to compare values.

In Visual Basic query expression syntax, an Aggregate Into Max() clause translates to an invocation of Max.

The following code example demonstrates how to use Max(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Int32)) to determine the maximum value in a sequence of projected values.

NoteNote

This code example uses an overload of this overloaded method that is different from the specific overload that this topic describes. To extend the example to this topic, change the body of the selector function.

Structure Pet
        Public Name As String 
        Public Age As Integer 
    End Structure 

    Sub MaxEx4()
        ' Create an array of Pet objects. 
        Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8}, _
                             New Pet With {.Name = "Boots", .Age = 4}, _
                             New Pet With {.Name = "Whiskers", .Age = 1}}

        ' Determine the "maximum" pet by passing a 
        ' lambda expression to Max() that sums the pet's age 
        ' and name length. 
        Dim max As Integer = pets.Max(Function(pet) _
                                          pet.Age + pet.Name.Length)

        ' Display the result.
        MsgBox("The maximum pet age plus name length is " & max)
    End Sub 

    ' This code produces the following output: 
    
    ' The maximum pet age plus name length is 14

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

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

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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