Enumerable.Max(Of TSource) Method (IEnumerable(Of TSource))

Returns the maximum value in a generic sequence.

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

'Declaration
<ExtensionAttribute> _
Public Shared Function Max(Of TSource) ( _
	source As IEnumerable(Of TSource) _
) As TSource

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable(Of TSource)
A sequence of values to determine the maximum value of.

Return Value

Type: TSource
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 is Nothing.

If type TSource implements IComparable(Of T), the Max(Of TSource)(IEnumerable(Of TSource)) method uses that implementation to compare values. Otherwise, if type TSource implements IComparable, that implementation is used to compare values.

If TSource is a reference type and the source sequence is empty or contains only values that are Nothing, this method returns Nothing.

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)) to determine the maximum value in a sequence of IComparable(Of T) objects.


    ' This class implements IComparable 
    ' and has a custom 'CompareTo' implementation.
    Class Pet
        Implements IComparable(Of Pet)

        Public Name As String
        Public Age As Integer

        ''' <summary>
        ''' Compares Pet objects by the sum of their age and name length.
        ''' </summary>
        ''' <param name="other">The Pet to compare this Pet to.</param>
        ''' <returns>-1 if this Pet's sum is 'less' than the other Pet,
        ''' 0 if they are equal,
        ''' or 1 if this Pet's sum is 'greater' than the other Pet.</returns>
        Function CompareTo(ByVal other As Pet) As Integer _
            Implements IComparable(Of Pet).CompareTo

            If (other.Age + other.Name.Length > Me.Age + Me.Name.Length) Then
                Return -1
            ElseIf (other.Age + other.Name.Length = Me.Age + Me.Name.Length) Then
                Return 0
            Else
                Return 1
            End If
        End Function
    End Class

    Sub MaxEx3()
        ' 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}}

        ' Find the "maximum" pet according to the 
        ' custom CompareTo() implementation.
        Dim max As Pet = pets.Max()

        ' Display the result.
        MsgBox("The 'maximum' animal is " & max.Name)
    End Sub

    ' This code produces the following output:
    '
    ' The 'maximum' animal is Barley



.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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