ParallelEnumerable::FirstOrDefault<TSource> Method (ParallelQuery<TSource>^)
Returns the first element of a parallel sequence, or a default value if the sequence contains no elements.
Assembly: System.Core (in System.Core.dll)
public: generic<typename TSource> [ExtensionAttribute] static TSource FirstOrDefault( ParallelQuery<TSource>^ source )
Parameters
- source
-
Type:
System.Linq::ParallelQuery<TSource>^
The sequence to return the first element of.
Return Value
Type: TSourcedefault(TSource) if source is empty; otherwise, the first element in source.
Type Parameters
- TSource
The type of the elements of source.
| Exception | Condition |
|---|---|
| OperationCanceledException | The query was canceled with the token passed in through WithCancellation. |
| ArgumentNullException | source is a null reference (Nothing in Visual Basic). |
| AggregateException | One or more exceptions occurred during the evaluation of the query. |
If the query is not ordered, then the first element is non-deterministic. For more information, see Order Preservation in PLINQ.
Available since 8
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1