const UInt32 PCF_RTSCTS    = 0x0002; // RTS (request-to-send)/CTS (clear-to-send) supported

The first sends an arbitrary structure (called txStruct) to another process.

   public IntPtr dwData;    // Any value the sender chooses.  Perhaps its main window handle?

// The first field, dwData, may contain anything the sender wishes; it is the equivalent of System.Object sender in an EventHandler.

C# Example 1 - send data:

// An example of sending a message containing a txStruct.

public SendMessage()

   SendMessage(hWnd, WM_COPYDATA, IntPtr.Zero, copyDataBuff);

    public string SenderName;

    public string SenderCompany;

    public string SenderDept;

    public string SenderBillingCode;

This structure is allocated by a user-mode application. It is a container for a reply that the application sends in response to a message received from a kernel-mode minifilter or minifilter instance.

        ///see Remark in KEYBDINPUT, SendInput, WM_KEYDOWN, and WM_KEYUP

    /// when reading messages and set it to empty or NULL when sending messages.

    /// sender of the message.

  /// A MapiRecipDesc structure contains information about a message sender or recipient.

    ///     0    MAPI_ORIG  Indicates the original sender of the message.

    /// Pointer to the display name of the message recipient or sender.

    /// Optional pointer to the recipient or sender's address; this address is provider-specific message

    /// to return valid entry identifiers for all recipients or senders listed in the address book.

    ''' when reading messages and set it to empty or NULL when sending messages.

    ''' sender of the message.

    ''' A MapiRecipDesc structure contains information about a message sender or recipient.

    '''     0    MAPI_ORIG  Indicates the original sender of the message.

    ''' Pointer to the display name of the message recipient or sender.

    ''' Optional pointer to the recipient or sender's address; this address is provider-specific message

    ''' to return valid entry identifiers for all recipients or senders listed in the address book.

   UCHAR   ncb_sto;        /* send timeout/sys timeout       */

    /// Application-defined message identifier. The system uses this identifier to send

    /// Shell_NotifyIcon. This member is only employed when using Shell_NotifyIcon to send an

        /// <summary>Handle to the device sending the data.</summary>

        ''' <summary>Handle to the device sending the data.</summary>

        /// Constructor for the command to send to the robot

        private void Form1_Load(object sender, System.EventArgs e)

I tried to use this to send files to the recycle bin. It failed (Marshal.GetLastWin32Error was 6, invalid handle) and sometimes threw a NullReferenceException. To make it work I did the following;

FileSystem.DeleteFile(path, UIOption.OnlyErrorDialogs, RecycleOption.SendToRecycleBin);

private void Form_Load(object sender, System.EventArgs e)

Have a look at SendInput for an example of where these constants are used.

   // For use with the INPUT struct, see SendInput for an example

    ' For use with the INPUT struct, see SendInput for an example

        SendMessage(parent, WM_SIZE, SIZE_RESTORED, 0);

Use this method to get the list of items out of a combo box using Windows API call (SendMessage). You need to

get the count of items in the combo box first (also with SendMessage api).

        Dim ptrLength As Integer = SendMessage(windowHandle, ComboBox_GetComboBoxTextLength, iPtr, zero)

        ' string builder to send

        SendMessage(windowHandle, ComboBox_GetComboBoxText, iPtr, winText)

Used in SendMessage API

  /// Indicates the original sender of the message.

  /// Client applications set this flag when sending a message.

  /// A dialog box should be displayed to prompt the user for recipients and other sending options.

    public static PropertyKey PKEY_IsSendToTarget = new PropertyKey( 0x28636AA6, 0x953D, 0x11D2, 0xB5, 0xD6, 0x00, 0xC0, 0x4F, 0xD9, 0x18, 0xD0, 33);

    public static PropertyKey PKEY_Message_SenderAddress = new PropertyKey( 0x0BE1C8E7, 0x1981, 0x4676, 0xAE, 0x14, 0xFD, 0xD7, 0x8F, 0x05, 0xA6, 0xE7, 100);

    public static PropertyKey PKEY_Message_SenderName = new PropertyKey( 0x0DA41CFA, 0xD224, 0x4A18, 0xAE, 0x2F, 0x59, 0x61, 0x58, 0xDB, 0x4B, 0x3A, 100);

    public static PropertyKey WPD_EMAIL_SENDER_ADDRESS = new PropertyKey(0x41F8F65A, 0x5484, 0x4782, 0xB1, 0x3D, 0x47, 0x40, 0xDD, 0x7C, 0x37, 0xC5, 10);

    public static PropertyKey WPD_COMMAND_SMS_SEND = new PropertyKey(0xAFC25D66, 0xFE0D, 0x4114, 0x90, 0x97, 0x97, 0x0C, 0x93, 0xE9, 0x20, 0xD1, 2);

    public static PropertyKey WPD_PROPERTY_MTP_EXT_TRANSFER_NUM_BYTES_TO_WRITE = new PropertyKey(0x4d545058, 0x1a2e, 0x4106, 0xa3, 0x57, 0x77, 0x1e, 0x8, 0x19, 0xfc, 0x56, 1010); // [ VT_UI4 ] : Input specifying the number of bytes to send to device in a series of write calls

const UInt32 SWP_NOSENDCHANGING  =0x0400;

    Const SWP_NOSENDCHANGING As Integer = &H400

const UInt32 SWP_NOSENDCHANGING  =0x0400;

        /// An error occurred in sending the command to the application.

        public const int RPC_S_SEND_INCOMPLETE = 1913;

        public const int ERROR_DS_LDAP_SEND_QUEUE_FULL = 8616;

        /// A request to send or receive data was disallowed because the socket is not connected and (when sending on a datagram socket using a sendto call) no address was supplied.

        /// A request to send or receive data was disallowed because the socket had already been shut down in that direction with a previous shutdown call.

        public const int WSA_QOS_SENDERS = 11006;

        /// There are no senders.

        public const int WSA_QOS_NO_SENDERS = 11007;

        /// Peer failed to send valid machine certificate

        /// The caller is dispatching an intertask SendMessage call and cannot call out via PostMessage.

        public const int RPC_E_CANTPOST_INSENDCALL = (int)(0x80010003 - 0x100000000);

        /// The client is trying to negotiate a context and the server requires user-to-user but didn't send a TGT reply.

private void frm_Activated(object sender, EventArgs e)

private void frm_Deactivate(object sender, EventArgs e)

The HidD_SetOutputReport routine sends an output report to a top-level collection.

Text1.Text = SendToUsbPrinter(”Hello world.”)

Function SendToUsbPrinter(PrintOut As String) As Boolean

SendToUsbPrinter = False

SendToUsbPrinter = True

private void button1_Click(object sender, System.EventArgs e)

        private static void CurrentDomain_ProcessExit(object sender, EventArgs e)

    Private Shared Sub CurrentDomain_ProcessExit(ByVal sender As Object, ByVal e As EventArgs)

        private static void CurrentDomain_ProcessExit(object sender, EventArgs e)

    Private Shared Sub CurrentDomain_ProcessExit(ByVal sender As Object, ByVal e As EventArgs)

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

private void shutdownToolStripMenuItem_Click(object sender, EventArgs e)

     DiskSmartSendDriveCommand = (EFileDevice.Disk << 16) | (0x0021 << 2) | EMethod.Buffered | (FileAccess.ReadWrite << 14),

   Private Const DFP_SEND_DRIVE_COMMAND As Integer = &H7C084

   Private Declare Function DeviceIoControl Lib "kernel32" (ByVal hDevice As Integer, ByVal dwIoControlCode As Integer, ByRef lpInBuffer As SENDCMDINPARAMS, ByVal nInBufferSize As Integer, ByRef lpOutBuffer As IntPtr, ByVal nOutBufferSize As Integer, ByRef lpBytesReturned As Integer, ByVal lpOverlapped As IntPtr) As Integer

   Structure SENDCMDINPARAMS

       Dim bDriveNumber As Byte    ' Physical drive number to send command to (0,1,2,3).

   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

       Dim SCIP As SENDCMDINPARAMS

    CLRRTS = 4, //Clears the RTS (request-to-send) signal.

    SETDTR = 5, //Sends the DTR (data-terminal-ready) signal.

    SETRTS = 3, //Sends the RTS (request-to-send) signal.

    // watching for CTS (Clear To Send)

    void watchdog_Tick(object sender, EventArgs e)

    private void cmdTest_Click(object sender, EventArgs e)

    protected void Page_Load(pbject sender, EventArgs e)

    public byte   ncb_sto;        /* send timeout/sys timeout       */

Sends a string to the debugger for display.

If you need a more accurate break time, you could lower the baud rate, send

There is a message (WM_SETTINGCHANGE) you can send in order to notify the active windows that there has been a configuration change using the SendMessageTimeout function.

Sending NULL to lpData and 0 to cbData will delete the file indicated by hUpdate.

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

    ,BINDSTATUS_SENDINGREQUEST

    Private Sub button1_Click(sender As Object, e As System.EventArgs) Handles button1.Click

    Private Sub button1_Click(sender As Object, e As System.EventArgs) Handles button1.Click

        /// The system does not send a message to the application when the user clicks the Cancel button.

    void SendControlMsg(UInt32 id, UInt32 uMsg, UInt32 wParam, UInt32 lParam, IntPtr pret);

    // to close the receiving and sending functions of the socket

        /// send without using routing tables

        /// partial send or recv for message xport

    public static extern int recvfrom(IntPtr Socket, IntPtr buf, int len, SendDataFlags flags, ref SockAddr from, IntPtr fromlen);

    public static int recvfrom(IntPtr Socket, IntPtr buf, int len, SendDataFlags flags, ref SockAddr from)

public static extern int SendTo (IntPtr Socket, IntPtr buff, int len, SendDataFlags flags, ref SockAddr To, int tomlen);

    public enum SendDataFlags

    /// <summary>Sends OOB data (stream-style socket such as SOCK_STREAM only)</summary>

System.Net.Sockets.Socket (class) Socket.SendTo () - better to use It))

If no error occurs, sendto returns the total number of bytes sent, which can be less than the number indicated by len. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

[DllImport("ws2_32.dll", EntryPoint="sendto")]

public static extern int SendTo (IntPtr Socket, IntPtr buff, int len, SendDataFlags flags, ref SockAddr To, int tomlen);

    public enum SendDataFlags

    /// <summary>Sends OOB data (stream-style socket such as SOCK_STREAM only)</summary>

System.Net.Sockets.Socket (class) Socket.SendTo () - better to use It))

If no error occurs, sendto returns the total number of bytes sent, which can be less than the number indicated by len. Otherwise, a value of SOCKET_ERROR is returned, and a specific error code can be retrieved by calling WSAGetLastError.

        SD_SEND = 1,

        SendBuffer = 0x1001,

        SendLowWater = 0x1003,

        SendTimeout = 0x1005,

        /// Offset to checksum for raw IP socket send.

        /// permit sending of broadcast msgs

        /// send buffer size

        /// send low-water mark

        /// send timeout