EnumerableMax Method
 

Returns the maximum value in a generic sequence.

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

public static TSource Max<TSource>(
	this IEnumerable<TSource> source
)
public:
generic<typename TSource>
[ExtensionAttribute]
static TSource Max(
	IEnumerable<TSource>^ source
)
static member Max<'TSource> : 
        source:IEnumerable<'TSource> -> 'TSource
<ExtensionAttribute>
Public Shared Function Max(Of TSource) (
	source As IEnumerable(Of TSource)
) As TSource

Parameters

source
Type:

A sequence of values to determine the maximum value of.

Return Value

Type: TSource

The maximum value in the sequence.

Type Parameters

TSource

The type of the elements of source.

Exception Condition
ArgumentNullException

source is null.

If type TSource implements IComparable, the Max 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 null, this method returns null.

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 to determine the maximum value in a sequence of IComparable objects.

/// <summary>
/// This class implements IComparable to be able to 
/// compare one Pet to another Pet.
/// </summary>
class Pet : IComparable<Pet>
{
    public string Name { get; set; }
    public int Age { get; set; }

    /// <summary>
    /// Compares this Pet to another Pet by 
    /// summing each Pet's age and name length.
    /// </summary>
    /// <param name="other">The Pet to compare this Pet to.</param>
    /// <returns>-1 if this Pet is 'less' than the other Pet, 
    /// 0 if they are equal,
    /// or 1 if this Pet is 'greater' than the other Pet.</returns>
    int IComparable<Pet>.CompareTo(Pet other)
    {
        int sumOther = other.Age + other.Name.Length;
        int sumThis = this.Age + this.Name.Length;

        if (sumOther > sumThis)
            return -1;
        else if (sumOther == sumThis)
            return 0;
        else
            return 1;
    }
}

public static void MaxEx3()
{
    Pet[] pets = { new Pet { Name="Barley", Age=8 },
                   new Pet { Name="Boots", Age=4 },
                   new Pet { Name="Whiskers", Age=1 } };

    Pet max = pets.Max();

    Console.WriteLine(
        "The 'maximum' animal is {0}.",
        max.Name);
}

/*
 This code produces the following output:

 The 'maximum' animal is Barley.
*/
' 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
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
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