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Collection(Of T).Count Property

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

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

'Declaration
Public ReadOnly Property Count As Integer
'Usage
Dim instance As Collection 
Dim value As Integer 

value = instance.Count

Property Value

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

Implements

ICollection(Of T).Count
ICollection.Count

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

The following code example demonstrates many of the properties and methods of Collection(Of T). The code example creates a collection of strings, uses the Add method to add several strings, displays the Count, and lists the strings. The example uses the IndexOf method to find the index of a string and the Contains method to determine whether a string is in the collection. The example inserts a string using the Insert method and retrieves and sets strings using the default Item property (the indexer in C#). The example removes strings by string identity using the Remove method and by index using the RemoveAt method. Finally, the Clear method is used to clear all strings from the collection.

Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

Public Class Demo

    Public Shared Sub Main() 

        Dim dinosaurs As New Collection(Of String)

        dinosaurs.Add("Psitticosaurus")
        dinosaurs.Add("Caudipteryx")
        dinosaurs.Add("Compsognathus")
        dinosaurs.Add("Muttaburrasaurus")

        Console.WriteLine("{0} dinosaurs:", dinosaurs.Count)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "IndexOf(""Muttaburrasaurus""): {0}", _
            dinosaurs.IndexOf("Muttaburrasaurus"))

        Console.WriteLine(vbLf & "Contains(""Caudipteryx""): {0}", _
            dinosaurs.Contains("Caudipteryx"))

        Console.WriteLine(vbLf & "Insert(2, ""Nanotyrannus"")")
        dinosaurs.Insert(2, "Nanotyrannus")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs(2): {0}", dinosaurs(2))

        Console.WriteLine(vbLf & "dinosaurs(2) = ""Microraptor""")
        dinosaurs(2) = "Microraptor"
        Display(dinosaurs)

        Console.WriteLine(vbLf & "Remove(""Microraptor"")")
        dinosaurs.Remove("Microraptor")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "RemoveAt(0)")
        dinosaurs.RemoveAt(0)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs.Clear()")
        dinosaurs.Clear()
        Console.WriteLine("Count: {0}", dinosaurs.Count)

    End Sub 

    Private Shared Sub Display(ByVal cs As Collection(Of String)) 
        Console.WriteLine()
        For Each item As String In cs
            Console.WriteLine(item)
        Next item
    End Sub 
End Class 

' This code example produces the following output: 

'4 dinosaurs: 

'Psitticosaurus 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 

'IndexOf("Muttaburrasaurus"): 3 

'Contains("Caudipteryx"): True 

'Insert(2, "Nanotyrannus") 

'Psitticosaurus 
'Caudipteryx 
'Nanotyrannus 
'Compsognathus 
'Muttaburrasaurus 

'dinosaurs(2): Nanotyrannus 

'dinosaurs(2) = "Microraptor" 

'Psitticosaurus 
'Caudipteryx 
'Microraptor 
'Compsognathus 
'Muttaburrasaurus 

'Remove("Microraptor") 

'Psitticosaurus 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 

'RemoveAt(0) 

'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 

'dinosaurs.Clear() 
'Count: 0

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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