Enumerable.Max(Of TSource) Method (IEnumerable(Of TSource), Func(Of TSource, Int64))

.NET Framework (current version)

Invokes a transform function on each element of a sequence and returns the maximum Int64 value.

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

Syntax

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

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, Int64)
A transform function to apply to each element.

Return Value

Type: System.Int64

The maximum value in the sequence.

Type Parameters

TSource: The type of the elements of source.

Exceptions

Exception	Condition
ArgumentNullException	source or selector is null.
InvalidOperationException	source contains no elements.

Remarks

The Max(Of TSource)(IEnumerable(Of TSource), Func(Of TSource, Int64)) method uses the Int64 implementation of IComparable(Of T) to compare values.

You can apply this method to a sequence of arbitrary values if you provide a function, selector, that projects the members of source into a numeric type, specifically Int64.

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

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