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

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

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
public static long Max<TSource>(
    this IEnumerable<TSource> source,
    Func<TSource, long> selector
)

Type Parameters

  • TSource
    The type of the elements of source.

Parameters

  • 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.

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.

Exceptions

Exception Condition
ArgumentNullException

source or selector is nullNothingnullptra null reference (Nothing in Visual Basic).

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 Enumerable.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.
      outputBlock.Text &= "The maximum pet age plus name length is " & max & vbCrLf
   End Sub

   ' This code produces the following output:
   '
   ' The maximum pet age plus name length is 14
      class Pet
      {
         public string Name { get; set; }
         public int Age { get; set; }
      }

      public static void MaxEx4()
      {
         Pet[] pets = { new Pet { Name="Barley", Age=8 },
                            new Pet { Name="Boots", Age=4 },
                            new Pet { Name="Whiskers", Age=1 } };

         int max = pets.Max(pet => pet.Age + pet.Name.Length);

         outputBlock.Text += String.Format(
             "The maximum pet age plus name length is {0}.",
             max) + "\n";
      }

      /*
       This code produces the following output:

       The maximum pet age plus name length is 14.
      */

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

See Also

Reference

Enumerable Class

Max Overload

System.Linq Namespace