TakeWhile(TSource) Method (ParallelQuery(TSource), Func(TSource, Int32, Boolean))

ParallelEnumerable.TakeWhile<TSource> Method (ParallelQuery<TSource>, Func<TSource, Int32, Boolean>)


Returns elements from a parallel sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.

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

public static ParallelQuery<TSource> TakeWhile<TSource>(
	this ParallelQuery<TSource> source,
	Func<TSource, int, bool> predicate


Type: System.Linq.ParallelQuery<TSource>

The sequence to return elements from.

Type: System.Func<TSource, Int32, Boolean>

A function to test each source element for a condition; the second parameter of the function represents the index of the source element.

Return Value

Type: System.Linq.ParallelQuery<TSource>

A sequence that contains elements from the input sequence that occur before the element at which the test no longer passes.

Type Parameters


The type of elements of source.

Exception Condition

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


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


More than MaxValue elements are enumerated by this query.


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

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
Return to top
© 2015 Microsoft