C# Signature:

[DllImport("kernel32.dll", SetLastError=true, ExactSpelling=true)]
static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress,
   IntPtr dwSize, AllocationType flAllocationType, MemoryProtection flProtect);

C# Signature:

  [DllImport("kernel32")]
  public static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

C# Signature:

    [DllImport("kernel32.dll", SetLastError = true, ExactSpelling = true)]
    static extern IntPtr VirtualAllocEx(IntPtr hProcess,
                        IntPtr lpAddress,
                        int dwSize,
                        AllocationType flAllocationType,
                        MemoryProtection flProtect);

VB.NET Signature:

<DllImport("kernel32.dll", SetLastError:=True, ExactSpelling:=True)> _
Private Function VirtualAllocEx(ByVal hProcess As IntPtr, ByVal lpAddress As IntPtr, _
     ByVal dwSize As IntPtr, ByVal flAllocationType As UInteger, _
     ByVal flProtect As UInteger) As IntPtr
End Function

Boo Signature:

[DllImport("kernel32.dll")]
def VirtualAllocEx(hProcess as IntPtr, lpAddress as IntPtr, dwSize as UInt32, flNewProtect as UInt32, lpflOldProtect as UInt32) as IntPtr:
     pass

User-Defined Types:

[Flags]
public enum AllocationType
{
     Commit = 0x1000,
     Reserve = 0x2000,
     Decommit = 0x4000,
     Release = 0x8000,
     Reset = 0x80000,
     Physical = 0x400000,
     TopDown = 0x100000,
     WriteWatch = 0x200000,
     LargePages = 0x20000000
}

[Flags]
public enum MemoryProtection
{
     Execute = 0x10,
     ExecuteRead = 0x20,
     ExecuteReadWrite = 0x40,
     ExecuteWriteCopy = 0x80,
     NoAccess = 0x01,
     ReadOnly = 0x02,
     ReadWrite = 0x04,
     WriteCopy = 0x08,
     GuardModifierflag = 0x100,
     NoCacheModifierflag = 0x200,
     WriteCombineModifierflag = 0x400
}

Notes:

None.

Tips & Tricks:

You can get the dwSize in C# with sizeof(TYPE) for blittable types or Marshal.SizeOf(typeof(TYPE)) for non-blittable types

Sample Code:

        IntPtr allocatedBaseAddress = VirtualAllocEx(process.Handle, IntPtr.Zero, buffer.Length, AllocationType.Commit | AllocationType.Reserve, MemoryProtection.ExecuteReadWrite);

Alternative Managed API:

The ManagedWindowsApi project (http://mwinapi.sourceforge.net) provides a ProcessMemoryChunk class to allocate and access memory of a different process.

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).