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

Returns the only element of a parallel sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.

Namespace:  System.Linq
Assembly:  System.Core (in System.Core.dll)

public static TSource SingleOrDefault<TSource>(
	this ParallelQuery<TSource> source,
	Func<TSource, bool> predicate
)

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.

predicate
Type: System.Func<TSource, Boolean>

A function to test an element for a condition.

Return Value

Type: TSource
The single element of the input sequence that satisfies the condition, or default() if no such element is found.

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

source is empty or multiple elements are returned.

.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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