FirstOrDefault(TSource) Method (ParallelQuery(TSource), Func(TSource, Boolean))

ParallelEnumerable.FirstOrDefault<TSource> Method (ParallelQuery<TSource>, Func<TSource, Boolean>)


Returns the first element of the parallel 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 FirstOrDefault<TSource>(
	this ParallelQuery<TSource> source,
	Func<TSource, bool> predicate


Type: System.Linq.ParallelQuery<TSource>

The sequence to return an element from.

Type: System.Func<TSource, Boolean>

A function to test each element for a condition.

Return Value

Type: TSource

default(TSource) if source is empty or if no element passes the test specified by predicate; otherwise, the first element in source that passes the test specified by predicate.

Type Parameters


The type of the elements of source.

Exception Condition

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


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


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.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Windows Phone
Available since 8.1
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