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ReadOnlyCollection(Of T).CopyTo Method

Copies the entire ReadOnlyCollection(Of T) to a compatible one-dimensional Array, starting at the specified index of the target array.

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

'Declaration
Public Sub CopyTo ( _
	array As T(), _
	index As Integer _
)
'Usage
Dim instance As ReadOnlyCollection 
Dim array As T()
Dim index As Integer

instance.CopyTo(array, index)

Parameters

array
Type: T()

The one-dimensional Array that is the destination of the elements copied from ReadOnlyCollection(Of T). The Array must have zero-based indexing.

index
Type: System.Int32

The zero-based index in array at which copying begins.

Implements

ICollection(Of T).CopyTo(T(), Int32)

ExceptionCondition
ArgumentNullException

array is Nothing.

ArgumentOutOfRangeException

index is less than zero.

ArgumentException

The number of elements in the source ReadOnlyCollection(Of T) is greater than the available space from index to the end of the destination array.

This method uses Array.Copy to copy the elements.

The elements are copied to the Array in the same order that the enumerator iterates through the ReadOnlyCollection(Of T).

This method is an O(n) operation, where n is Count.

The following code example demonstrates several members of the ReadOnlyCollection(Of T) class. The code example creates a List(Of T) of strings and adds four dinosaur names to it. The code example then wraps the list in a ReadOnlyCollection(Of T).

After demonstrating the Count, Contains, Item, and IList.IndexOf members, the code example shows that the ReadOnlyCollection(Of T) is just a wrapper for the original List(Of T) by adding a new item to the List(Of T) and displaying the contents of the ReadOnlyCollection(Of T).

Finally, the code example creates an array larger than the collection and uses the CopyTo method to insert the elements of the collection into the middle of the array.

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

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs As New List(Of String)

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

        Dim readOnlyDinosaurs As _
            New ReadOnlyCollection(Of String)(dinosaurs)

        Console.WriteLine()
        For Each dinosaur As String In readOnlyDinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & "Count: {0}", _
            readOnlyDinosaurs.Count)

        Console.WriteLine(vbLf & "Contains(""Deinonychus""): {0}", _
            readOnlyDinosaurs.Contains("Deinonychus"))

        Console.WriteLine(vbLf & _
            "readOnlyDinosaurs(3): {0}", readOnlyDinosaurs(3))

        Console.WriteLine(vbLf & "IndexOf(""Compsognathus""): {0}", _
            readOnlyDinosaurs.IndexOf("Compsognathus"))

        Console.WriteLine(vbLf & "Insert into the wrapped List:")
        Console.WriteLine("Insert(2, ""Oviraptor"")")
        dinosaurs.Insert(2, "Oviraptor")

        Console.WriteLine()
        For Each dinosaur As String In readOnlyDinosaurs
            Console.WriteLine(dinosaur)
        Next 

        Dim dinoArray(readOnlyDinosaurs.Count + 1) As String
        readOnlyDinosaurs.CopyTo(dinoArray, 1)

        Console.WriteLine(vbLf & "Copied array has {0} elements:", _
            dinoArray.Length)
        For Each dinosaur As String In dinoArray
            Console.WriteLine("""{0}""", dinosaur)
        Next 

   End Sub 
End Class 

' This code example produces the following output: 

'Tyrannosaurus 
'Amargasaurus 
'Deinonychus 
'Compsognathus 

'Count: 4 

'Contains("Deinonychus"): True 

'readOnlyDinosaurs(3): Compsognathus 

'IndexOf("Compsognathus"): 3 

'Insert into the wrapped List: 
'Insert(2, "Oviraptor") 

'Tyrannosaurus 
'Amargasaurus 
'Oviraptor 
'Deinonychus 
'Compsognathus 

'Copied array has 7 elements: 
'"" 
'"Tyrannosaurus" 
'"Amargasaurus" 
'"Oviraptor" 
'"Deinonychus" 
'"Compsognathus" 
'""

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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