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List.CopyTo Method (Int32, T[], Int32, Int32)

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

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

public void CopyTo (
	int index,
	T[] array,
	int arrayIndex,
	int count
)
public void CopyTo (
	int index, 
	T[] array, 
	int arrayIndex, 
	int count
)
public function CopyTo (
	index : int, 
	array : T[], 
	arrayIndex : int, 
	count : int
)
Not applicable.

Parameters

index

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

array

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

arrayIndex

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

count

The number of elements to copy.

Exception typeCondition

ArgumentNullException

array is a 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

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

-or-

arrayIndex is equal to or greater than the length of array.

-or-

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

This method uses System.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.

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

The following code example demonstrates all three overloads of the CopyTo method. A List 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 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
 */

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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