ParallelEnumerable.First<TSource> Method (ParallelQuery<TSource>)
Returns the first element of a parallel sequence.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Linq.ParallelQuery<TSource>
The sequence to return the first element of.
Return Value
Type: TSourceThe first element in the specified sequence.
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. |
| InvalidOperationException | source contains no elements. |
If the query is not ordered, then the first element is non-deterministic. For more information, see Order Preservation in PLINQ.
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.
