MSDN Library

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

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)

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

Type Parameters


The type of the elements of source.


Type: System.Collections.Generic.IEnumerable<TSource>
A sequence of values to determine the maximum value of.
Type: System.Func<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<TSource>. When you use instance method syntax to call this method, omit the first parameter.


source or selector is null.


source contains no elements.

The Max<TSource>(IEnumerable<TSource>, Func<TSource, Int64>) method uses the Int64 implementation of IComparable<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.

The following code example demonstrates how to use Max<TSource>(IEnumerable<TSource>, Func<TSource, Int32>) to determine the maximum value in a sequence of projected values.


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.

      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.


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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