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List<T>.CopyTo Method (Int32, array<T[], Int32, Int32)

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

Copies a range of elements from the List<T> to a compatible one-dimensional array, starting at the specified index of the target array.

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

Syntax

'Declaration
Public Sub CopyTo ( _
    index As Integer, _
    array As T(), _
    arrayIndex As Integer, _
    count As Integer _
)

public void CopyTo(
    int index,
    T[] array,
    int arrayIndex,
    int count
)

Parameters

  • array
    Type: array<T[]
    The one-dimensional Array that is the destination of the elements copied from List<T>. The Array must have zero-based indexing.
  • arrayIndex
    Type: System.Int32
    The zero-based index in array at which copying begins.

Exceptions

Exception Condition
ArgumentNullException

array is nulla null reference (Nothing in Visual Basic).
ArgumentOutOfRangeException

index is less than 0.

-or-

arrayIndex is less than 0.

-or-

count is less than 0.
ArgumentException

The number of elements from index to the end of the source List<T> is greater than the available space from arrayIndex to the end of the destination array.

Remarks

This method uses Array.Copy to copy the elements.

The elements are copied to the Array in the same order in which the enumerator iterates through the List<T>.

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

Examples

The following code example demonstrates all three overloads of the CopyTo method. A List<T> of strings is created and populated with 5 strings. An empty string array of 15 elements is created, and the CopyTo(array<T[]) method overload is used to copy all the elements of the list to the array beginning at the first element of the array. The CopyTo(array<T[], Int32) method overload is used to copy all the elements of the list to the array beginning at array index 6 (leaving index 5 empty). Finally, the CopyTo(Int32, array<T[], Int32, Int32) method overload is used to copy 3 elements from the list, beginning with index 2, to the array beginning at array index 12 (leaving index 11 empty). The contents of the array are then displayed.

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)

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

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

      ' Declare an array with 15 elements (0 through 14).
      Dim array(14) As String

      dinosaurs.CopyTo(array)
      dinosaurs.CopyTo(array, 6)
      dinosaurs.CopyTo(2, array, 12, 3)

      outputBlock.Text &= vbLf & "Contents of the array:" & vbCrLf
      For Each dinosaur As String In array
         outputBlock.Text &= dinosaur & vbCrLf
      Next

   End Sub
End Class

' This code example produces the following output:
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Brachiosaurus
'Compsognathus
'
'Contents of the array:
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Brachiosaurus
'Compsognathus
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Brachiosaurus
'Compsognathus
'
'Mamenchisaurus
'Brachiosaurus
'Compsognathus

using System;
using System.Collections.Generic;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      List<string> dinosaurs = new List<string>();

      dinosaurs.Add("Tyrannosaurus");
      dinosaurs.Add("Amargasaurus");
      dinosaurs.Add("Mamenchisaurus");
      dinosaurs.Add("Brachiosaurus");
      dinosaurs.Add("Compsognathus");

      outputBlock.Text += "\n";
      foreach (string dinosaur in dinosaurs)
      {
         outputBlock.Text += dinosaur + "\n";
      }

      // Declare an array with 15 elements.
      string[] array = new string[15];

      dinosaurs.CopyTo(array);
      dinosaurs.CopyTo(array, 6);
      dinosaurs.CopyTo(2, array, 12, 3);

      outputBlock.Text += "\nContents of the array:" + "\n";
      foreach (string dinosaur in array)
      {
         outputBlock.Text += dinosaur + "\n";
      }
   }
}

/* This code example produces the following output:

Tyrannosaurus
Amargasaurus
Mamenchisaurus
Brachiosaurus
Compsognathus

Contents of the array:
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Brachiosaurus
Compsognathus

Tyrannosaurus
Amargasaurus
Mamenchisaurus
Brachiosaurus
Compsognathus

Mamenchisaurus
Brachiosaurus
Compsognathus
 */

Version Information

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

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.