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

April 12, 2014

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

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)
public static Nullable<double> Max<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, Nullable<double>> selector
)

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>
A sequence of values to determine the maximum value of.
selector
Type: System.Func<TSource, Nullable<Double>>
A transform function to apply to each element.

Return Value

Type: System.Nullable<Double>
The value of type Nullable<Double> in C# or Nullable(Of Double) in Visual Basic that corresponds to 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.
ExceptionCondition
ArgumentNullException

source or selector is null.

The Max<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Double>>) method uses the Double 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 Nullable<Double> in C# or Nullable(Of Double) in Visual Basic.

In Visual Basic query expression syntax, an Aggregate Into Max() clause translates to an invocation of Enumerable.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.

NoteNote:

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.
      */



Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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