Desktop Functions:

   Smart Device Functions:

Show Recent Changes
Subscribe (RSS)
Misc. Pages
Helpful Tools
Suggested Reading
Website TODO List
Support Forum
Download Visual Studio Add-In

Terms of Use
Privacy Policy
CopyMemory (urlmon)
Copies a block of memory from one location to another.

C# Signature:

[DllImport("kernel32.dll", EntryPoint = "CopyMemory", SetLastError = false)]

public static extern void CopyMemory(IntPtr dest, IntPtr src, uint count);

VB Signature:

Public Declare Auto Sub CopyMemory lib "kernel32.dll" Alias "CopyMemory"(destination As IntPtr, source As IntPtr, length As UInteger)

<DllImport("kernel32.dll", SetLastError:= True, EntryPoint:= "CopyMemory")>
Public Shared Sub CopyMemory(destination As IntPtr, source As IntPtr, length As UInteger)
End Sub

User-Defined Types:


Alternative Managed API:

Do you know one? Please contribute it!



Tips & Tricks:

Please add some!

Sample Code:

    // static void Main()
    // {
    //   const int size = 200;
    //   IntPtr memorySource = Marshal.AllocHGlobal(size);
    //   IntPtr memoryTarget = Marshal.AllocHGlobal(size);
    //   CopyMemory(memoryTarget,memorySource,size);
    // }

     [DllImport("kernel32.dll", SetLastError=true, EntryPoint="CopyMemory")
     public static void CopyMemory(void* destination, void* source, uint length);

     public static unsafe void Main()
     int[] data = Enumerable.Range(1, 1000000);
     int size = data.Length * sizeof(int);
     byte[] dst = new byte[size]
     fixed (byte* pd = dst){ fixed(int* ps = data){ CopyMemory(pd, ps, size); } }
     Console.WriteLine("10 data result : {0}", BitConverter.ToString(dst, 0, 10));
     Console.WriteLine("Is assuming equals : {0}", BitConverter.ToInt32(dst, 0) == data[0] &&
                               BitConverter.ToInt32(dst, dst.GetUpperBound(0) - sizeof(int)) == data[data.GetUpperBound(0)]);

Sample Code VB:

   Public Module CopyMemoryTest

      Public Declare Auto Sub CopyMemory lib "kernel32.dll" Alias "CopyMemory"(destination As IntPtr, source As IntPtr, length As UInteger)

      Public Sub Main(ParamArray args As String())
    Dim source As Byte() = File.ReadAllBytes("C:\Windows\explorer.exe"),
        destination(source.GetUpperBound(0)) As Byte,
        length As UInteger = CUInt(source.Length),
        sourcePtr As IntPtr = Marshal.UnsafeAddrOfPinnedArrayElement(source, 0),
        targetPtr As IntPtr = Marshal.UnsafeAddrOfPinnedArrayElement(target, 0)
    Dim sw As Stopwatch = Stopwatch.StartNew()
    CopyMemory(targetPtr, sourcePtr, length)
    Console.WriteLine("Total time to copy {0:N0} bytes = {1}", new TimeSpan(sw.ElapsedTicks))
    Using sha = New System.Security.Cryptography.SHA512Managed
      Dim sourceChecksum = sha.ComputeHash(source),
          destinationCheksum = sha.ComputeHash(destination),
          isEquals = True
      For i = 0 To sourceChecksum.GetUpperBound(0)
        If sourceChecksum(i) <> destinationChecksum(i) Then
           Console.WriteLine("The copy memory is bad, some of data are not copied..")
           IsEquals = False
           Exit For
        End If
      Next i
      If isEquals Then Console.WriteLine("The copy memory is perfectly copy all bytes.")
    End Using
    Console.ReadKey().Key = ConsoleKeys.R Then
    End If
    sw = Nothing
    Erase source, destination
      End Sub

   End Module


CopyMemory on MSDN

Please edit this page!

Do you have...

  • helpful tips or sample code to share for using this API in managed code?
  • corrections to the existing content?
  • variations of the signature you want to share?
  • additional languages you want to include?

Select "Edit This Page" on the right hand toolbar and edit it! Or add new pages containing supporting types needed for this API (structures, delegates, and more).

Access directly from VS:
Terms of Use
Edit This Page
Find References
Show Printable Version