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: 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 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
