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
DeviceIoControl (kernel32)

C# Signature:

[DllImport("kernel32.dll", ExactSpelling = true, SetLastError = true, CharSet = CharSet.Auto)]
static extern bool DeviceIoControl(IntPtr hDevice, uint dwIoControlCode,
IntPtr lpInBuffer, uint nInBufferSize,
IntPtr lpOutBuffer, uint nOutBufferSize,
out uint lpBytesReturned, IntPtr lpOverlapped);

VB Signature:

<DllImport("kernel32.dll", ExactSpelling:=True, SetLastError:=True, CharSet:=CharSet.Auto)> _
   Private Shared Function DeviceIoControl(ByVal hDevice As IntPtr, _
     ByVal dwIoControlCode As Int32, ByVal lpInBuffer As IntPtr, _
     ByVal nInBufferSize As Int32, ByVal lpOutBuffer As IntPtr, _
     ByVal nOutBufferSize As Int32, ByRef lpBytesReturned As Int32, _
     ByVal lpOverlapped As System.Threading.NativeOverlapped) As Boolean
   End Function

User-Defined Types:



hDevice - To retrieve a handle to a volume, call CreateFile with the lpFileName parameter set to a string of the following form: \\.\DriveLetter:


tHandle = CreateFile("\\.\\C:", FileAccess.Read, FileShare.ReadWrite, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero)

Tips & Tricks:

This is great for interacting with devices; now perhaps someone can help with the SetupDi calls to actually discover the device handles, etc...? If you are able to conquer it (I wasn't) toss me a mail at dotnet at richardgoodwin dot com


Sample Code:

Public ReadOnly Property CardID() As String
   Dim dwErrorCode As FarcConstants
   Dim dwBytesReceived As Int32
   Dim ip As IntPtr = Marshal.AllocHGlobal(13)
   Dim erg As String
   If DeviceIoControl(hDriver, IOCTL_FARC_GET_CARDID, Nothing, 0, ip, 13, dwBytesReceived, Nothing) Then
     erg = Marshal.PtrToStringAnsi(ip)
     dwErrorCode = Marshal.GetLastWin32Error
     Throw New InvalidOperationException("Get Card ID fails. Errorcode: " & _
       dwErrorCode.ToString, New System.ComponentModel.Win32Exception(dwErrorCode))
   End If
   Return erg
  End Get
End Property

Alternative Managed API:

Do you know one? Please contribute it!


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
Find References
Show Printable Version