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Marshal.Copy Method (IntPtr, Byte(), Int32, Int32)

Copies data from an unmanaged memory pointer to a managed 8-bit unsigned integer array.

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

'Declaration
<SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags := SecurityPermissionFlag.UnmanagedCode)> _
Public Shared Sub Copy ( _
	source As IntPtr, _
	destination As Byte(), _
	startIndex As Integer, _
	length As Integer _
)
'Usage
Dim source As IntPtr 
Dim destination As Byte()
Dim startIndex As Integer 
Dim length As Integer 

Marshal.Copy(source, destination, startIndex, _
	length)

Parameters

source
Type: System.IntPtr

The memory pointer to copy from.

destination
Type: System.Byte()

The array to copy to.

startIndex
Type: System.Int32

The zero-based index into the array where Copy should start.

length
Type: System.Int32

The number of array elements to copy.

ExceptionCondition
ArgumentNullException

source, destination, startIndex, or length is Nothing.

Unmanaged, C-style arrays do not contain bounds information, which prevents the startIndex and length parameters from being validated. Thus, the unmanaged data corresponding to the source parameter populates the managed array regardless of its usefulness. You must initalize the managed array with the appropriate size before calling the Marshal.Copy method.

NoteNote:

This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

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

Imports System
Imports System.Runtime.InteropServices



Module Example


    Sub Main()
        ' Create a managed array. 
        Dim managedArray As Byte() = {1, 2, 3, 4}

        ' Initialize unmanged memory to hold the array. 
        Dim size As Integer = Marshal.SizeOf(managedArray(0)) * managedArray.Length

        Dim pnt As IntPtr = 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. 
            Dim managedArray2(managedArray.Length) As Byte

            Marshal.Copy(pnt, managedArray2, 0, managedArray.Length)

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

        Finally 
            ' Free the unmanaged memory.
            Marshal.FreeHGlobal(pnt)
        End Try 

    End Sub 
End Module

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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