Marshal.Copy Method (IntPtr, Char(), Int32, Int32)
Copies data from an unmanaged memory pointer to a managed character array.
Assembly: mscorlib (in mscorlib.dll)
'Declaration <SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags := SecurityPermissionFlag.UnmanagedCode)> _ Public Shared Sub Copy ( _ source As IntPtr, _ destination As Char(), _ startIndex As Integer, _ length As Integer _ ) 'Usage Dim source As IntPtr Dim destination As Char() Dim startIndex As Integer Dim length As Integer Marshal.Copy(source, destination, startIndex, _ length)
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.
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) 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 Char 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.