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

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Returns the number of elements in a sequence.

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


<ExtensionAttribute> _
Public Shared Function Count(Of TSource) ( _
    source As IEnumerable(Of TSource) _
) As Integer
public static int Count<TSource>(
    this IEnumerable<TSource> source

Type Parameters

  • TSource
    The type of the elements of source.


Return Value

Type: System.Int32
The number of elements in the input 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 in source is larger than MaxValue.


If the type of source implements ICollection<T>, that implementation is used to obtain the count of elements. Otherwise, this method determines the count.

Use the LongCount method when you expect and want to allow the result to be greater than MaxValue.

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


The following code example demonstrates how to use Count<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"}

         ' Count the number of items in the array.
         Dim numberOfFruits As Integer = fruits.Count()
         ' Display the output.
         outputBlock.Text &= "There are " & numberOfFruits & " fruits in the collection." & vbCrLf
      Catch e As OverflowException
         outputBlock.Text &= "The count is too large to store as an Int32. Try using LongCount() instead." & vbCrLf
      End Try

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

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

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

      catch (OverflowException)
         outputBlock.Text += "The count is too large to store as an Int32." + "\n";
         outputBlock.Text += "Try using the LongCount() method instead." + "\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.