Enumerable.TryGetNonEnumeratedCount Method (System.Linq) (original) (raw)

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Attempts to determine the number of elements in a sequence without forcing an enumeration.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static bool TryGetNonEnumeratedCount(System::Collections::Generic::IEnumerable<TSource> ^ source, [Runtime::InteropServices::Out] int % count);

public static bool TryGetNonEnumeratedCount<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, out int count);

static member TryGetNonEnumeratedCount : seq<'Source> * int -> bool

<Extension()>
Public Function TryGetNonEnumeratedCount(Of TSource) (source As IEnumerable(Of TSource), ByRef count As Integer) As Boolean

Type Parameters

TSource

The type of the elements of source.

Parameters

source

IEnumerable

A sequence that contains elements to be counted.

count

Int32

When this method returns, contains the number of elements in source, or 0 if the count couldn't be determined without enumeration.

Returns

true if the count of source can be determined without enumeration; otherwise, false.

Remarks

The method performs a series of type tests, identifying common subtypes whose count can be determined without enumerating. This includes ICollection, ICollection, and internal types used in the LINQ implementation.

The method is typically a constant-time operation, but ultimately this depends on the complexity characteristics of the underlying collection's implementation.

Applies to