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Marshal.Copy Method (Char[], Int32, IntPtr, Int32)

Copies data from a one-dimensional, managed character array to an unmanaged memory pointer.

Namespace:  System.Runtime.InteropServices
Assembly:  mscorlib (in mscorlib.dll)
public static void Copy(
	char[] source,
	int startIndex,
	IntPtr destination,
	int length
)

Parameters

source
Type: System.Char[]

The one-dimensional array to copy from.

startIndex
Type: System.Int32

The zero-based index in the source array where copying should start.

destination
Type: System.IntPtr

The memory pointer to copy to.

length
Type: System.Int32

The number of array elements to copy.

ExceptionCondition
ArgumentOutOfRangeException

startIndex and length are not valid.

ArgumentNullException

startIndex, destination, or length is null.

You can use this method to copy a subset of a one-dimensional managed array to an unmanaged C-style array.

The following example copies an array to unmanaged memory and then copies the unmanaged array back to managed memory.

// Remember that the actual size of System.Char in unmanaged memory is 2. 
using System;
using System.Runtime.InteropServices;

class Example
{

    static void Main()
    {
        // Create a managed array. 
        char[] managedArray = new char[1000];
        managedArray[0] = 'a';
        managedArray[1] = 'b';
        managedArray[2] = 'c';
        managedArray[3] = 'd';
        managedArray[999] = 'Z';

        // Initialize unmanged memory to hold the array. 
        // int size = Marshal.SizeOf(managedArray[0]) * managedArray.Length;  // Incorrect 
        int size = Marshal.SystemDefaultCharSize * managedArray.Length;       // Correct


        IntPtr pnt = Marshal.AllocHGlobal(size);

        try
        {
            // Copy the array to unmanaged memory.
            Marshal.Copy(managedArray, 0, pnt, managedArray.Length);

            // Copy the unmanaged array back to another managed array. 

            char[] managedArray2 = new char[managedArray.Length];

            Marshal.Copy(pnt, managedArray2, 0, managedArray.Length);
            Console.WriteLine("Here is the roundtripped array: {0} {1} {2} {3} {4}",
                               managedArray2[0], managedArray2[1], managedArray2[2], managedArray2[3],
                               managedArray2[999]);

            Console.WriteLine("The array was coppied to unmanaged memory and back.");

        }
        finally
        {
            // Free the unmanaged memory.
            Marshal.FreeHGlobal(pnt);
        }



    }

}

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

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

    requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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