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ReadOnlyCollection.CopyTo Method

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

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

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

Parameters

array

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

index

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

Exception typeCondition

ArgumentNullException

array is a null reference (Nothing in Visual Basic).

ArgumentOutOfRangeException

index is less than zero.

ArgumentException

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

-or-

The number of elements in the source ReadOnlyCollection is greater than the available space from index 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 that the enumerator iterates through the ReadOnlyCollection.

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

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

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

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.

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

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

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

        ReadOnlyCollection<string> readOnlyDinosaurs = 
            new ReadOnlyCollection<string>(dinosaurs);

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

        Console.WriteLine("\nCount: {0}", readOnlyDinosaurs.Count);

        Console.WriteLine("\nContains(\"Deinonychus\"): {0}", 
            readOnlyDinosaurs.Contains("Deinonychus"));

        Console.WriteLine("\nreadOnlyDinosaurs[3]: {0}", 
            readOnlyDinosaurs[3]);

        Console.WriteLine("\nIndexOf(\"Compsognathus\"): {0}", 
            readOnlyDinosaurs.IndexOf("Compsognathus"));

        Console.WriteLine("\nInsert into the wrapped List:");
        Console.WriteLine("Insert(2, \"Oviraptor\")");
        dinosaurs.Insert(2, "Oviraptor");

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

        string[] dinoArray = new string[readOnlyDinosaurs.Count + 2];
        readOnlyDinosaurs.CopyTo(dinoArray, 1);

        Console.WriteLine("\nCopied array has {0} elements:", 
            dinoArray.Length);
        foreach( string dinosaur in dinoArray )
        {
            Console.WriteLine("\"{0}\"", dinosaur);
        }
    }
}

/* 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 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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