ParallelEnumerable::SingleOrDefault<TSource> Method (ParallelQuery<TSource>)
Returns the only element of a parallel sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.
Assembly: System.Core (in System.Core.dll)
[ExtensionAttribute] public: generic<typename TSource> static TSource SingleOrDefault( ParallelQuery<TSource>^ source )
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Linq::ParallelQuery<TSource>
The sequence to return the single element of.
Return Value
Type: TSourceThe single element of the input sequence, or default() if the sequence contains no elements.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type ParallelQuery<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 |
|---|---|
| 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. |
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.
