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.
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: TSourcedefault(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. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).| Exception | Condition |
|---|---|
| ArgumentNullException | source or predicate 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); Console.WriteLine("The last number that rounds to 50 is {0}.", last50); double last40 = numbers.LastOrDefault(n => Math.Round(n) == 40.0); Console.WriteLine( "The last number that rounds to 40 is {0}.", last40 == 0.0 ? "<DOES NOT EXIST>" : last40.ToString()); /* 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>. */
Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
