Enumerable.LongCount<TSource> Method (IEnumerable<TSource>)

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Returns an Int64 that represents the total number of elements in a sequence.

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


<ExtensionAttribute> _
Public Shared Function LongCount(Of TSource) ( _
    source As IEnumerable(Of TSource) _
) As Long
public static long LongCount<TSource>(
    this IEnumerable<TSource> source

Type Parameters

  • TSource
    The type of the elements of source.


Return Value

Type: System.Int64
The number of elements in the source sequence.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter.


Exception Condition

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


The number of elements exceeds MaxValue.


Use this method rather than Count when you expect the result to be greater than MaxValue.

In Visual Basic query expression syntax, an Aggregate Into LongCount() clause translates to an invocation of LongCount.


The following code example demonstrates how to use LongCount<TSource>(IEnumerable<TSource>) to count the elements in an array.

      ' Create an array of strings.
      Dim fruits() As String = _
          {"apple", "banana", "mango", "orange", "passionfruit", "grape"}

      ' Get the number of items in the array.
      Dim count As Long = fruits.LongCount()

      ' Display the result.
      outputBlock.Text &= "There are " & count & " fruits in the collection." & vbCrLf

      ' This code produces the following output:
      ' There are 6 fruits in the collection.

      string[] fruits = { "apple", "banana", "mango", 
                               "orange", "passionfruit", "grape" };

      long count = fruits.LongCount();

      outputBlock.Text += String.Format("There are {0} fruits in the collection.", count) + "\n";

       This code produces the following output:

       There are 6 fruits in the collection.

Version Information


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.