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.NET Framework Class Library

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

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

Namespace:  System.Linq
Assemblies:   System.Linq (in System.Linq.dll)
  System.Core (in System.Core.dll)
<ExtensionAttribute> _
Public Shared Function LongCount(Of TSource) ( _
	source As IEnumerable(Of TSource) _
) As Long

Type Parameters

TSource

The type of the elements of source.

Parameters

source
Type: System.Collections.Generic.IEnumerable<TSource>

An IEnumerable<T> that contains the elements to be counted.

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. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).
Exception Condition
ArgumentNullException

source is null.

OverflowException

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.
        MsgBox("There are " & count & " fruits in the collection.")

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library