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List<T>.CopyTo Method (T[])

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

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

public void CopyTo(
	T[] array
)

Parameters

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

ExceptionCondition
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.

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.

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(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
 */


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

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