List(Of T).Count Property

Gets the number of elements actually contained in the List(Of T).

Namespace:  System.Collections.Generic
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public ReadOnly Property Count As Integer

Property Value

Type: System.Int32
The number of elements actually contained in the List(Of T).

Implements

ICollection(Of T).Count
ICollection.Count

Capacity is the number of elements that the List(Of T) can store before resizing is required. Count is the number of elements that are actually in the List(Of T).

Capacity is always greater than or equal to Count. If Count exceeds Capacity while adding elements, the capacity is increased by automatically reallocating the internal array before copying the old elements and adding the new elements.

Retrieving the value of this property is an O(1) operation.

The following code example shows the value of the Count property at various points in the life of a list. After the list has been created and populated and its elements displayed, the Capacity and Count properties are displayed. These properties are displayed again after the TrimExcess method has been called, and again after the contents of the list are cleared.


Imports System.Collections.Generic

Public Class Example

   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      Dim dinosaurs As New List(Of String)

      outputBlock.Text &= String.Format(vbLf & "Capacity: {0}", dinosaurs.Capacity) & vbCrLf

      dinosaurs.Add("Tyrannosaurus")
      dinosaurs.Add("Amargasaurus")
      dinosaurs.Add("Mamenchisaurus")
      dinosaurs.Add("Deinonychus")
      dinosaurs.Add("Compsognathus")

      outputBlock.Text &= vbCrLf
      For Each dinosaur As String In dinosaurs
         outputBlock.Text &= dinosaur & vbCrLf
      Next

      outputBlock.Text &= String.Format(vbLf & "Capacity: {0}", dinosaurs.Capacity) & vbCrLf
      outputBlock.Text &= String.Format("Count: {0}", dinosaurs.Count) & vbCrLf

      outputBlock.Text &= vbLf & String.Format("Contains(""Deinonychus"": {0}", _
          dinosaurs.Contains("Deinonychus")) & vbCrLf

      outputBlock.Text &= String.Format(vbLf & "Insert(2, ""Compsognathus"")") & vbCrLf
      dinosaurs.Insert(2, "Compsognathus")

      outputBlock.Text &= vbCrLf
      For Each dinosaur As String In dinosaurs
         outputBlock.Text &= dinosaur & vbCrLf
      Next

      outputBlock.Text &= String.Format(vbLf & "dinosaurs(3): {0}", dinosaurs(3)) & vbCrLf

      outputBlock.Text &= vbLf & "Remove(""Compsognathus"")" & vbCrLf
      dinosaurs.Remove("Compsognathus")

      outputBlock.Text &= vbCrLf
      For Each dinosaur As String In dinosaurs
         outputBlock.Text &= dinosaur & vbCrLf
      Next

      dinosaurs.TrimExcess()
      outputBlock.Text &= vbLf & "TrimExcess()" & vbCrLf
      outputBlock.Text &= String.Format("Capacity: {0}", dinosaurs.Capacity) & vbCrLf
      outputBlock.Text &= String.Format("Count: {0}", dinosaurs.Count) & vbCrLf

      dinosaurs.Clear()
      outputBlock.Text &= vbLf & "Clear()" & vbCrLf
      outputBlock.Text &= String.Format("Capacity: {0}", dinosaurs.Capacity) & vbCrLf
      outputBlock.Text &= String.Format("Count: {0}", dinosaurs.Count) & vbCrLf
   End Sub
End Class

' This code example produces the following output:
'
'Capacity: 0
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'Capacity: 8
'Count: 5
'
'Contains("Deinonychus"): True
'
'Insert(2, "Compsognathus")
'
'Tyrannosaurus
'Amargasaurus
'Compsognathus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'dinosaurs(3): Mamenchisaurus
'
'Remove("Compsognathus")
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'TrimExcess()
'Capacity: 5
'Count: 5
'
'Clear()
'Capacity: 5
'Count: 0


Silverlight

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.

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