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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, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

  • SecurityCriticalAttribute 

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

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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