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Enumerable.Max<TSource> Method (IEnumerable<TSource>, Func<TSource, Int32>)

Invokes a transform function on each element of a sequence and returns the maximum Int32 value.

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

public static int Max<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, int> 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, Int32>
A transform function to apply to each element.

Return Value

Type: System.Int32
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. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).


source or selector is null.


source contains no elements.

The Max<TSource>(IEnumerable<TSource>, Func<TSource, Int32>) method uses the Int32 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 Int32.

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.

            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);

                    "The maximum pet age plus name length is {0}.",

             This code produces the following output:

             The maximum pet age plus name length is 14.

.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.