Export (0) Print
Expand All

Enumerable.LastOrDefault<TSource> Method (IEnumerable<TSource>, Func<TSource, Boolean>)

Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.

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

public static TSource LastOrDefault<TSource>(
	this IEnumerable<TSource> source,
	Func<TSource, bool> predicate
)

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>
An IEnumerable<T> to return an element from.
predicate
Type: System.Func<TSource, Boolean>
A function to test each element for a condition.

Return Value

Type: TSource
default(TSource) if the sequence is empty or if no elements pass the test in the predicate function; otherwise, the last element that passes the test in the predicate function.

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 predicate is null.

The default value for reference and nullable types is null.

The following code example demonstrates how to use LastOrDefault<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>) by passing in a predicate. In the second call to the method, there is no element in the sequence that satisfies the condition.


      double[] numbers = { 49.6, 52.3, 51.0, 49.4, 50.2, 48.3 };

      double last50 = numbers.LastOrDefault(n => Math.Round(n) == 50.0);

      outputBlock.Text += String.Format("The last number that rounds to 50 is {0}.", last50) + "\n";

      double last40 = numbers.LastOrDefault(n => Math.Round(n) == 40.0);

      outputBlock.Text += String.Format(
          "The last number that rounds to 40 is {0}.",
          last40 == 0.0 ? "<DOES NOT EXIST>" : last40.ToString()) + "\n";

      /*
       This code produces the following output:

       The last number that rounds to 50 is 50.2.
       The last number that rounds to 40 is <DOES NOT EXIST>.
      */



Silverlight

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.

Community Additions

ADD
Show:
© 2014 Microsoft