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

Copies data from an unmanaged memory pointer to a managed character array.

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

Public Shared Sub Copy ( _
	source As IntPtr, _
	destination As Char(), _
	startIndex As Integer, _
	length As Integer _
Dim source As IntPtr
Dim destination As Char()
Dim startIndex As Integer
Dim length As Integer

Marshal.Copy(source, destination, startIndex, length)
public static void Copy (
	IntPtr source, 
	char[] destination, 
	int startIndex, 
	int length
public static function Copy (
	source : IntPtr, 
	destination : char[], 
	startIndex : int, 
	length : int
Not applicable.



The memory pointer to copy from.


The array to copy to.


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


The number of array elements to copy.

Exception typeCondition


source, destination, startIndex, or length is a null reference (Nothing in Visual Basic).

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.


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 Char() = ("abcd").ToCharArray

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

        Dim pnt As IntPtr = Marshal.AllocHGlobal(size)

            ' 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 Char

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

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

            ' Free the unmanaged memory.
        End Try

    End Sub
End Module

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, 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, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0