C# Signature:

[DllImport("user32.dll", SetLastError=true)]
static extern uint SendInput(uint nInputs, INPUT [] pInputs, int cbSize);

VB.NET Signature:

Private Declare Function SendInput Lib "user32.dll" (ByVal cInputs As Integer, ByRef pInputs As INPUT, ByVal cbSize As Integer) As Integer

C# User-Defined Types:

[StructLayout(LayoutKind.Sequential)]
struct MOUSEINPUT
{
      int dx;
      int dy;
      int mouseData;
      int dwFlags;
      int time;
      IntPtr dwExtraInfo;
}

[StructLayout(LayoutKind.Sequential)]
struct KEYBDINPUT
{
      short wVk;
      short wScan;
      int dwFlags;
      int time;
      IntPtr dwExtraInfo;
}

[StructLayout(LayoutKind.Sequential)]
struct HARDWAREINPUT
{
      int uMsg;
      short wParamL;
      short wParamH;
}

[StructLayout(LayoutKind.Explicit)]
struct INPUT
{
      [FieldOffset(0)]
      int type;
      [FieldOffset(4)]
      MOUSEINPUT mi;
      [FieldOffset(4)]
      KEYBDINPUT ki;
      [FieldOffset(4)]
      HARDWAREINPUT hi;
}

[DllImport("user32.dll")]

static extern IntPtr GetMessageExtraInfo();

VB.NET User-Defined Types:

<StructLayout(LayoutKind.Explicit)> _
    Private Structure INPUT
        <FieldOffset(0)> Dim dwType As Integer
        <FieldOffset(4)> Dim mouseInput As mouseInput
        <FieldOffset(4)> Dim keyboardInput As KEYBDINPUT
        <FieldOffset(4)> Dim hardwareInput As hardwareInput
    End Structure

        <StructLayout(LayoutKind.Explicit)> _
    Private Structure KEYBDINPUT
        <FieldOffset(0)> Public wVk As Short
        <FieldOffset(2)> Public wScan As Short
        <FieldOffset(4)> Public dwFlags As Integer
        <FieldOffset(8)> Public time As Integer
        <FieldOffset(12)> Public dwExtraInfo As IntPtr
    End Structure

        <StructLayout(LayoutKind.Explicit)> _
    Private Structure HARDWAREINPUT
        <FieldOffset(0)> Public uMsg As Integer
        <FieldOffset(4)> Public wParamL As Short
        <FieldOffset(6)> Public wParamH As Short
    End Structure

        <StructLayout(LayoutKind.Explicit)> _
    Private Structure MOUSEINPUT
        <FieldOffset(0)> Public dx As Integer
        <FieldOffset(4)> Public dy As Integer
        <FieldOffset(8)> Public mouseData As Integer
        <FieldOffset(12)> Public dwFlags As Integer
        <FieldOffset(16)> Public time As Integer
        <FieldOffset(20)> Public dwExtraInfo As IntPtr
    End Structure

Notes:

You'll need 3 constants to use this function,.here they are.

[c#]

const int INPUT_MOUSE = 0;

const int INPUT_KEYBOARD = 1;

const int INPUT_HARDWARE = 2;

[/c#]

I don't know how these definitions would be written in VB.NET, sorry.

*******************

(This code posted by Anh Phuong (http://360.yahoo.com/naphuonghic))

Code VB here:

Const INPUT_MOUSE As Integer = 0

Const INPUT_KEYBOARD As Integer = 1

Const INPUT_HARDWARE As Integer = 2

********************

Tips & Tricks:

windows CE universal core virtual key code compact chart http://msdn2.microsoft.com/en-us/library/aa926323.aspx

Sample Code:

// It might be better to write this code as a single call to SendInput passing
// all the key downs and keys ups in one array.  If you do this, SendInput
// guarantees that no other keys get inbetween the whole sequence.  As is stands,
// a "real" key transition could in theory sneak in the middle - and if it did
// it would inherit the states of shift, control, etc this program had set up.

class Test
{
    public enum VK : ushort
    {
    SHIFT        = 0x10,
    CONTROL          = 0x11,
    MENU         = 0x12,
    ESCAPE           = 0x1B,
    BACK         = 0x08,
    TAB          = 0x09,
    RETURN           = 0x0D,
    PRIOR        = 0x21,
    NEXT         = 0x22,
    END          = 0x23,
    HOME         = 0x24,
    LEFT         = 0x25,
    UP           = 0x26,
    RIGHT        = 0x27,
    DOWN         = 0x28,
    SELECT           = 0x29,
    PRINT        = 0x2A,
    EXECUTE          = 0x2B,
    SNAPSHOT         = 0x2C,
    INSERT           = 0x2D,
    DELETE           = 0x2E,
    HELP         = 0x2F,
    NUMPAD0          = 0x60,
    NUMPAD1          = 0x61,
    NUMPAD2          = 0x62,
    NUMPAD3          = 0x63,
    NUMPAD4          = 0x64,
    NUMPAD5          = 0x65,
    NUMPAD6          = 0x66,
    NUMPAD7          = 0x67,
    NUMPAD8          = 0x68,
    NUMPAD9          = 0x69,
    MULTIPLY         = 0x6A,
    ADD          = 0x6B,
    SEPARATOR        = 0x6C,
    SUBTRACT         = 0x6D,
    DECIMAL          = 0x6E,
    DIVIDE           = 0x6F,
    F1           = 0x70,
    F2           = 0x71,
    F3           = 0x72,
    F4           = 0x73,
    F5           = 0x74,
    F6           = 0x75,
    F7           = 0x76,
    F8           = 0x77,
    F9           = 0x78,
    F10          = 0x79,
    F11          = 0x7A,
    F12          = 0x7B,
    OEM_1        = 0xBA,   // ',:' for US
    OEM_PLUS         = 0xBB,   // '+' any country
    OEM_COMMA        = 0xBC,   // ',' any country
    OEM_MINUS        = 0xBD,   // '-' any country
    OEM_PERIOD       = 0xBE,   // '.' any country
    OEM_2        = 0xBF,   // '/?' for US
    OEM_3        = 0xC0,   // '`~' for US
    MEDIA_NEXT_TRACK     = 0xB0,
    MEDIA_PREV_TRACK     = 0xB1,
    MEDIA_STOP           = 0xB2,
    MEDIA_PLAY_PAUSE     = 0xB3,
    LWIN       =0x5B,
    RWIN       =0x5C
    }

    public struct KEYBDINPUT
    {
    public ushort wVk;
    public ushort wScan;
    public uint dwFlags;
    public long time;
    public uint dwExtraInfo;
    };
    [StructLayout(LayoutKind.Explicit,Size=28)]
    public struct INPUT
    {
    public uint type;
    public KEYBDINPUT ki;
    };

    void Test()
    {
    INPUT structInput;
    structInput = new INPUT();
    structInput.type = Win32Consts.INPUT_KEYBOARD;

    // Key down shift, ctrl, and/or alt
    structInput.ki.wScan = 0;
    structInput.ki.time = 0;
    structInput.ki.dwFlags = 0;
    structInput.ki.dwExtraInfo = Win32.GetMessageExtraInfo();
    if (Shift)
    {
        structInput.ki.wVk = (ushort)VK.SHIFT;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Ctrl)
    {
        structInput.ki.wVk = (ushort)VK.CONTROL;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Alt)
    {
        structInput.ki.wVk = (ushort)VK.MENU;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Win)
    {
        structInput.ki.wVk = (ushort)VK.LWIN;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    // Key down the actual key-code
    structInput.ki.wVk = vk;
    intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    // Key up the actual key-code
    structInput.ki.dwFlags = Win32Consts.KEYEVENTF_KEYUP;
    intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    // Key up shift, ctrl, and/or alt
    if (Shift)
    {
        structInput.ki.wVk = (ushort)VK.SHIFT;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Ctrl)
    {
        structInput.ki.wVk = (ushort)VK.CONTROL;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Alt)
    {
        structInput.ki.wVk = (ushort)VK.MENU;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Win)
    {
        structInput.ki.wVk = (ushort)VK.LWIN;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    }
}

VB.NET Sample Code:

Imports System.Runtime.InteropServices

Public Class Form1

    Private tb As New TextBox
    Private WithEvents but1 As New Button

    Sub New()
    InitializeComponent()
    tb = New TextBox : tb.Location = New Point(10, 10)
    but1 = New Button : but1.Location = New Point(10, 40)
    but1.Text = "example"
    Me.Controls.Add(but1) : Me.Controls.Add(tb)
    End Sub

    Private Sub DoMouse(ByVal flags As NativeMethods.MOUSEEVENTF, ByVal newPoint As Point)
    Dim input As New NativeMethods.INPUT
    Dim mi As New NativeMethods.MOUSEINPUT
    input.dwType = NativeMethods.InputType.Mouse
    input.mi = mi
    input.mi.dwExtraInfo = IntPtr.Zero
    ' mouse co-ords: top left is (0,0), bottom right is (65535, 65535)
    ' convert screen co-ord to mouse co-ords...
    input.mi.dx = newPoint.X * (65535 / Screen.PrimaryScreen.Bounds.Width)
    input.mi.dy = newPoint.Y * (65535 / Screen.PrimaryScreen.Bounds.Height)
    input.mi.time = 0
    input.mi.mouseData = 0  ' can be used for WHEEL event see msdn
    input.mi.dwFlags = flags
    Dim cbSize As Integer = Marshal.SizeOf(GetType(NativeMethods.INPUT))
    Dim result As Integer = NativeMethods.SendInput(1, input, cbSize)
    If result = 0 Then Debug.WriteLine(Marshal.GetLastWin32Error)
    End Sub

    Private Sub DoKeyBoard(ByVal flags As NativeMethods.KEYEVENTF, ByVal key As Keys)
    Dim input As New NativeMethods.INPUT
    Dim ki As New NativeMethods.KEYBDINPUT
    input.dwType = NativeMethods.InputType.Keyboard
    input.ki = ki
    input.ki.wVk = Convert.ToInt16(key)
    input.ki.wScan = 0
    input.ki.time = 0
    input.ki.dwFlags = flags
    input.ki.dwExtraInfo = IntPtr.Zero
    Dim cbSize As Integer = Marshal.SizeOf(GetType(NativeMethods.INPUT))
    Dim result As Integer = NativeMethods.SendInput(1, input, cbSize)
    If result = 0 Then Debug.WriteLine(Marshal.GetLastWin32Error)
    End Sub

    Private Sub but1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles but1.Click
    'move to the textbox, click it to focus, keydown some chars...
    ' get textbox location in screen co-ords
    Dim tbLocation As Point = Me.PointToScreen(Me.tb.Location)
    ' nudge it into the tb
    tbLocation.X += 5
    tbLocation.Y += 5
    ' move to the TB. it is a MOVE event, and we use ABSOLUTE co-ordinates
    DoMouse(NativeMethods.MOUSEEVENTF.MOVE Or NativeMethods.MOUSEEVENTF.ABSOLUTE, tbLocation)
    ' click the TB
    DoMouse(NativeMethods.MOUSEEVENTF.LEFTDOWN, New Point(0, 0))
    ' release the mouse
    DoMouse(NativeMethods.MOUSEEVENTF.LEFTUP, New Point(0, 0))
    ' the key codes are virtual keycodes (see mdsn)
    ' I'm using a shortcut to save space - casting chars to ints
    ' if you want to change case, you need to send a shift key with the letter...
    Dim message As String = "HELLO WORLD"
    For Each c As Char In message
        Dim key As UInteger = Convert.ToInt16(c)
        DoKeyBoard(0, key)  ' key down is 0 - no flag...
        DoKeyBoard(NativeMethods.KEYEVENTF.KEYUP, key)
    Next
    DoKeyBoard(0, Keys.Decimal) ' example using keys enum which I think matches the VKEY values
    DoKeyBoard(NativeMethods.KEYEVENTF.KEYUP, Keys.Decimal)
    End Sub

End Class

Public Class NativeMethods

    <DllImport("user32.dll", SetLastError:=True)> _
    Friend Shared Function SendInput(ByVal cInputs As Int32, ByRef pInputs As INPUT, ByVal cbSize As Int32) As Int32
    End Function

    <StructLayout(LayoutKind.Explicit, pack:=1, Size:=28)> _
    Friend Structure INPUT
    <FieldOffset(0)> Public dwType As InputType
    <FieldOffset(4)> Public mi As MOUSEINPUT
    <FieldOffset(4)> Public ki As KEYBDINPUT
    <FieldOffset(4)> Public hi As HARDWAREINPUT
    End Structure

    <StructLayout(LayoutKind.Sequential, pack:=1)> _
    Friend Structure MOUSEINPUT
    Public dx As Int32
    Public dy As Int32
    Public mouseData As Int32
    Public dwFlags As MOUSEEVENTF
    Public time As Int32
    Public dwExtraInfo As IntPtr
    End Structure

    <StructLayout(LayoutKind.Sequential, pack:=1)> _
    Friend Structure KEYBDINPUT
    Public wVk As Int16
    Public wScan As Int16
    Public dwFlags As KEYEVENTF
    Public time As Int32
    Public dwExtraInfo As IntPtr
    End Structure

    <StructLayout(LayoutKind.Sequential, pack:=1)> _
    Friend Structure HARDWAREINPUT
    Public uMsg As Int32
    Public wParamL As Int16
    Public wParamH As Int16
    End Structure

    Friend Enum InputType As Integer
    Mouse = 0
    Keyboard = 1
    Hardware = 2
    End Enum

    <Flags()> _
    Friend Enum MOUSEEVENTF As Integer
    MOVE = &H1
    LEFTDOWN = &H2
    LEFTUP = &H4
    RIGHTDOWN = &H8
    RIGHTUP = &H10
    MIDDLEDOWN = &H20
    MIDDLEUP = &H40
    XDOWN = &H80
    XUP = &H100
    VIRTUALDESK = &H400
    WHEEL = &H800
    ABSOLUTE = &H8000
    End Enum

    <Flags()> _
    Friend Enum KEYEVENTF As Integer
    EXTENDEDKEY = 1
    KEYUP = 2
    [UNICODE] = 4
    SCANCODE = 8
    End Enum

End Class

Alternative Managed API:

Here is a managed solution: I think it works only in 2.0. Someone please verify.

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemWindowsFormsSendKeysClassTopic.asp

Please note that there is an unresolved issue using the SendKeys class in Windows Vista RC1 (Build 5536).

More specifically you may encounter a "Hook cannot be created." exception.

Please also note that there is an unresolved issue using the SendKeys class if ie7 is the target app.

More specifically, extra characters may be added to the input stream.

Do you know one? Please contribute it!

I found that using SendKeys to send {TAB} works OK but +{TAB} (i.e. shift-tab) doesn't; IE7 executes a forward-tab in both cases. Using the above routines, the following successfully does a shift-tab in IE7:

DoKeyBoard(0, Keys.ShiftKey)

DoKeyBoard(0, Keys.Tab)

DoKeyBoard(NativeMethods.KEYEVENTF.KEYUP, Keys.Tab)

DoKeyBoard(NativeMethods.KEYEVENTF.KEYUP, Keys.ShiftKey)

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