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ParallelEnumerable.First(TSource) Method (ParallelQuery(TSource), Func(TSource, Boolean))

Returns the first element in a parallel sequence that satisfies a specified condition.

Namespace:  System.Linq
Assemblies:   System.Linq.Parallel (in System.Linq.Parallel.dll)
  System.Core (in System.Core.dll)

static member First : 
        source:ParallelQuery<'TSource> * 
        predicate:Func<'TSource, bool> -> 'TSource 

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Linq.ParallelQuery(TSource)

The sequence to return an element from.

predicate
Type: System.Func(TSource, Boolean)

A function to test each element for a condition.

Return Value

Type: TSource
The first element in the sequence that passes the test in the specified predicate function.

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).

ExceptionCondition
OperationCanceledException

The query was canceled with the token passed in through WithCancellation.

ArgumentNullException

source or predicate is a null reference (Nothing in Visual Basic).

AggregateException

One or more exceptions occurred during the evaluation of the query.

InvalidOperationException

No element in source satisfies the condition in predicate.

If the query is not ordered, then the first element is non-deterministic. For more information, see Order Preservation in PLINQ.

.NET Framework

Supported in: 4.6, 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1
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