List<T>.CopyTo Method

Definition

Namespace:

System.Collections.Generic

Assembly:

System.Collections.dll

Copies the List<T> or a portion of it to an array.

Overloads

CopyTo(T[], Int32)	Copies the entire List<T> to a compatible one-dimensional array, starting at the specified index of the target array.
CopyTo(Int32, T[], Int32, Int32)	Copies a range of elements from the List<T> to a compatible one-dimensional array, starting at the specified index of the target array.
CopyTo(T[])	Copies the entire List<T> to a compatible one-dimensional array, starting at the beginning of the target array.

Examples

The following 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(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(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, 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.

using namespace System;
using namespace System::Collections::Generic;

void main()
{
    List<String^>^ dinosaurs = gcnew List<String^>();

    dinosaurs->Add("Tyrannosaurus");
    dinosaurs->Add("Amargasaurus");
    dinosaurs->Add("Mamenchisaurus");
    dinosaurs->Add("Brachiosaurus");
    dinosaurs->Add("Compsognathus");

    Console::WriteLine();
    for each(String^ dinosaurs in dinosaurs )
    {
        Console::WriteLine(dinosaurs);
    }

    // Create an array of 15 strings.
    array<String^>^ arr = gcnew array<String^>(15);

    dinosaurs->CopyTo(arr);
    dinosaurs->CopyTo(arr, 6);
    dinosaurs->CopyTo(2, arr, 12, 3);

    Console::WriteLine("\nContents of the array:");
    for each(String^ dinosaurs in arr )
    {
        Console::WriteLine(dinosaurs);
    }
}

/* This code example produces the following output:

Tyrannosaurus
Amargasaurus
Mamenchisaurus
Brachiosaurus
Deinonychus
Tyrannosaurus
Compsognathus

IndexOf("Tyrannosaurus"): 0

IndexOf("Tyrannosaurus", 3): 5

IndexOf("Tyrannosaurus", 2, 2): -1
 */

using System;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        List<string> dinosaurs = new List<string>();

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

        Console.WriteLine();
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }

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

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

        Console.WriteLine("\nContents of the array:");
        foreach(string dinosaur in array)
        {
            Console.WriteLine(dinosaur);
        }
    }
}

/* 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
 */

Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs As New List(Of String)

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

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        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)

        Console.WriteLine(vbLf & "Contents of the array:")
        For Each dinosaur As String In array
            Console.WriteLine(dinosaur)
        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

CopyTo(T[], Int32)

Source:

List.cs

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

public:
 virtual void CopyTo(cli::array <T> ^ array, int arrayIndex);

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

abstract member CopyTo : 'T[] * int -> unit
override this.CopyTo : 'T[] * int -> unit

Public Sub CopyTo (array As T(), arrayIndex As Integer)

Parameters

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

Int32

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

Implements

CopyTo(T[], Int32)

Exceptions

ArgumentNullException

array is null.

ArgumentOutOfRangeException

arrayIndex is less than 0.

ArgumentException

The number of elements in 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.

CopyTo(Int32, T[], Int32, Int32)

Source:

List.cs

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

public:
 void CopyTo(int index, cli::array <T> ^ array, int arrayIndex, int count);

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

member this.CopyTo : int * 'T[] * int * int -> unit

Public Sub CopyTo (index As Integer, array As T(), arrayIndex As Integer, count As Integer)

Parameters

index

Int32

The zero-based index in the source List<T> at which copying begins.

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

Int32

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

count

Int32

The number of elements to copy.

Exceptions

ArgumentNullException

array is null.

ArgumentOutOfRangeException

index is less than 0.

-or-

arrayIndex is less than 0.

-or-

count is less than 0.

ArgumentException

index is equal to or greater than the Count of the source List<T>.

-or-

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.

CopyTo(T[])

Source:

List.cs

Copies the entire List<T> to a compatible one-dimensional array, starting at the beginning of the target array.

public:
 void CopyTo(cli::array <T> ^ array);

public void CopyTo (T[] array);

member this.CopyTo : 'T[] -> unit

Public Sub CopyTo (array As T())

Parameters

array

T[]

The one-dimensional Array that is the destination of the elements copied from List<T>. The Array must have zero-based indexing.

Exceptions

ArgumentNullException

array is null.

ArgumentException

The number of elements in the source List<T> is greater than the number of elements that the destination array can contain.

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.