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CopyTo Method

String.CopyTo Method

Copies a specified number of characters from a specified position in this instance to a specified position in an array of Unicode characters.

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

public void CopyTo(
	int sourceIndex,
	char[] destination,
	int destinationIndex,
	int count


Type: System.Int32

The index of the first character in this instance to copy.

Type: System.Char[]

An array of Unicode characters to which characters in this instance are copied.

Type: System.Int32

The index in destination at which the copy operation begins.

Type: System.Int32

The number of characters in this instance to copy to destination.


destination is null.


sourceIndex, destinationIndex, or count is negative


sourceIndex does not identify a position in the current instance.


destinationIndex does not identify a valid index in the destination array.


count is greater than the length of the substring from startIndex to the end of this instance


count is greater than the length of the subarray from destinationIndex to the end of the destination array.

This method copies count characters from the sourceIndex position of this instance to the destinationIndex position of destination character array. This method does not resize the destination character array; it must have a sufficient number of elements to accommodate the copied characters or the method throws an ArgumentOutOfRangeException.

sourceIndex and destinationIndex are zero-based.

The following example demonstrates the CopyTo method.

using System;

public class CopyToTest {
    public static void Main() {

        // Embed an array of characters in a string 
        string strSource = "changed";
    char [] destination = { 'T', 'h', 'e', ' ', 'i', 'n', 'i', 't', 'i', 'a', 'l', ' ',
                'a', 'r', 'r', 'a', 'y' };

        // Print the char array
        Console.WriteLine( destination );

        // Embed the source string in the destination string
        strSource.CopyTo ( 0, destination, 4, strSource.Length );

        // Print the resulting array
        Console.WriteLine( destination );

        strSource = "A different string";

        // Embed only a section of the source string in the destination
        strSource.CopyTo ( 2, destination, 3, 9 );

        // Print the resulting array
        Console.WriteLine( destination );
// The example displays the following output: 
//       The initial array 
//       The changed array 
//       Thedifferentarray

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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