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

.NET Framework (current version)

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)

Syntax

<ExtensionAttribute>
Public Shared Function Max(Of TSource, TResult) (
	source As IEnumerable(Of TSource),
	selector As Func(Of TSource, TResult)
) As TResult

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.

Type Parameters

TSource: The type of the elements of source.

TResult: The type of the value returned by selector.

Exceptions

Exception	Condition
ArgumentNullException	source or selector is null.

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.

Examples

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.

Note
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

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