ParallelEnumerable.FirstOrDefault Method

Definition

Returns the first element of a parallel sequence, or a default value if the sequence contains no elements.

Overloads

FirstOrDefault<TSource>(ParallelQuery<TSource>)

Returns the first element of a parallel sequence, or a default value if the sequence contains no elements.

FirstOrDefault<TSource>(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.

FirstOrDefault<TSource>(ParallelQuery<TSource>)

Source:
ParallelEnumerable.cs
Source:
ParallelEnumerable.cs
Source:
ParallelEnumerable.cs

Returns the first element of a parallel sequence, or a default value if the sequence contains no elements.

C#
public static TSource FirstOrDefault<TSource>(this System.Linq.ParallelQuery<TSource> source);
C#
public static TSource? FirstOrDefault<TSource>(this System.Linq.ParallelQuery<TSource> source);

Type Parameters

TSource

The type of the elements of source.

Parameters

source
ParallelQuery<TSource>

The sequence to return the first element of.

Returns

TSource

default(TSource) if source is empty; otherwise, the first element in source.

Exceptions

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

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

Remarks

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

See also

Applies to

.NET 9 and other versions
Product Versions
.NET Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1
UWP 10.0

FirstOrDefault<TSource>(ParallelQuery<TSource>, Func<TSource,Boolean>)

Source:
ParallelEnumerable.cs
Source:
ParallelEnumerable.cs
Source:
ParallelEnumerable.cs

Returns the first element of the parallel sequence that satisfies a condition or a default value if no such element is found.

C#
public static TSource FirstOrDefault<TSource>(this System.Linq.ParallelQuery<TSource> source, Func<TSource,bool> predicate);
C#
public static TSource? FirstOrDefault<TSource>(this System.Linq.ParallelQuery<TSource> source, Func<TSource,bool> predicate);

Type Parameters

TSource

The type of the elements of source.

Parameters

source
ParallelQuery<TSource>

The sequence to return an element from.

predicate
Func<TSource,Boolean>

A function to test each element for a condition.

Returns

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.

Exceptions

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

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

Remarks

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

See also

Applies to

.NET 9 and other versions
Product Versions
.NET Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1
UWP 10.0