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Posted 4 Jun 2004


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Keyboard Events Simulation using keybd_event() function

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4.88/5 (65 votes)
4 Jun 2004CPOL2 min read
A short description of keybd_event() function for beginners.


Simulation of a keyboard input is a well known concept for those who are all familiar with Visual Basic. SendKeys() in Visual Basic does all the things, if you want to do anything without keyboard. But what is in SendKeys() function? What does it do? Can we do such a thing with Visual C++? This article is the answer. I think this will be useful for beginners who are all just trying to do something different with VC++. Let us get into the steps…

Function Syntax

void keybd_event(BYTE bVirtualKey, BYTE bScanCode, 
                         DWORD dwFlags, DWORD dwExtraInfo);
  • bVirtualKey //Virtual Keycode of keys. E.g., VK_RETURN, VK_TAB…
  • bScanCode //Scan Code value of keys. E.g., 0xb8 for “Left Alt” key.
  • dwFlags //Flag that is set for key state. E.g., KEYEVENTF_KEYUP.
  • dwExtraInfo //32-bit extra information about keystroke.

Function Details:

  • bVirtualKey

    Virtual keycode that has to be send as key input. The following are the available predefined virtual key codes:


    Character key can be converted into virtual key using VkKeyScan(TCHAR ch) function.

  • bScanCode

    Scan code is the hardware key code for the key (make and break codes). The following are the available scan codes (break code will be used in this parameter).

    Image 1

    Image 2

  • dwFlags

    A set of flag bits that specify various aspects of function operation. An application can use any combination of the following predefined constant values to set the flags.

    KEYEVENTF_EXTENDEDKEYIf specified, the scan code was preceded by a prefix byte having the value 0xE0 (224).
    KEYEVENTF_KEYUPIf specified, the key is being released. If not specified, the key is being depressed.
  • dwExtraInfo

    32-bit extra information along with the keyboard input.

    Image 3

Example Code

// Simulating a Alt+Tab keystroke
keybd_event(VK_MENU,0xb8,0 , 0); //Alt Press
keybd_event(VK_TAB,0x8f,0 , 0); // Tab Press
keybd_event(VK_TAB,0x8f, KEYEVENTF_KEYUP,0); // Tab Release
keybd_event(VK_MENU,0xb8,KEYEVENTF_KEYUP,0); // Alt Release

// Simulating a Ctrl+A keystroke
keybd_event(VK_CONTROL,0x9d,0 , 0); // Ctrl Press
keybd_event(VkKeyScan(‘A’),0x9e,0 , 0); // ‘A’ Press
keybd_event(VkKeyScan(‘A’),0x9e, KEYEVENTF_KEYUP,0); // ‘A’ Release
keybd_event(VK_CONTROL,0x9d,KEYEVENTF_KEYUP,0); // Ctrl Release


This article may not be that much detailed. None of the articles can satisfy one's expectations. But, each article should be a seed for your technical growth. Thus, I believe that this would be a seed. Thank you all.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Naren Neelamegam
Software Developer
India India
Naren started coding during 1999 with FORTRAN, then COBOL, PASCAL, C, C++, VC++ ..... C#, Java, ASP so on, till today. He claims himself as techie who loves coding, but he is not even sure which technology or platform he loves, most of the time Windows, some time WinCE, some time Linux, nowadays Android and embedded platforms. He can do some query stuffs with Oracle, SQL Server, MySQL. He strongly believes that C/C++ is a must for all programmers, "if you know C/C++, you can do programming on any language". He is an electronic gadget guy who likes to buy small gadgets all the time, at least he will do window shopping on a gadget shop. His interest always have been with Automation in any form, call it a little automated program sitting in his Laptop or a home automation program runs on his mobile. Apart from coding, he likes to do...???

Comments and Discussions

Suggestion* Pin
Member 1440490421-May-19 0:14
MemberMember 1440490421-May-19 0:14 
Questionkeyboard Pin
opium_2100210016-Jan-14 20:34
Memberopium_2100210016-Jan-14 20:34 
GeneralMy vote of 4 Pin
MD. Mohiuddin Ahmed16-Dec-12 6:22
MemberMD. Mohiuddin Ahmed16-Dec-12 6:22 
Questionwhat handle window to simulation ? if no active window simulate to where .please help me ! Pin
tieulamtu202118-Sep-12 22:54
Membertieulamtu202118-Sep-12 22:54 
Questionhow can i download this code? Pin
Member 811215027-Jul-11 18:06
MemberMember 811215027-Jul-11 18:06 
GeneralSendkeys Modification of Above Code for Citrix Pin
Andrewiski30-Aug-10 5:30
MemberAndrewiski30-Aug-10 5:30 
QuestionHow to Use this Example to Send Tab to Citrix Pin
Andrewiski26-Aug-10 10:47
MemberAndrewiski26-Aug-10 10:47 
AnswerRe: How to Use this Example to Send Tab to Citrix Pin
Andrewiski26-Aug-10 10:52
MemberAndrewiski26-Aug-10 10:52 
GeneralSimulate key from service Pin
friendship forever11-Nov-08 15:44
Memberfriendship forever11-Nov-08 15:44 
GeneralNEED HEPL!!!!!!!! Pin
sekharsam9-Jul-08 23:06
Membersekharsam9-Jul-08 23:06 
GeneralNeed a Help Pin
sekharsam9-Jul-08 20:03
Membersekharsam9-Jul-08 20:03 
GeneralRe: Need a Help Pin
bryan_f4-Mar-09 3:06
Memberbryan_f4-Mar-09 3:06 
Questionkeep key pressed Pin
SilverV29-Apr-08 6:08
MemberSilverV29-Apr-08 6:08 
GeneralNotebook FN Key Pin
snakeyeyess16-Apr-08 2:46
Membersnakeyeyess16-Apr-08 2:46 
Generalvirtual keyboard Pin
themancer12-Sep-07 9:40
Memberthemancer12-Sep-07 9:40 
Generalsendkeys sucks :) Pin
nekropatolog5-Aug-07 23:09
Membernekropatolog5-Aug-07 23:09 
GeneralA couple of notes on this article Pin
CPU Killer5-Aug-07 12:21
MemberCPU Killer5-Aug-07 12:21 
QuestionHow to simulate press and hold a character key? Pin
lc1234-Mar-07 12:04
Memberlc1234-Mar-07 12:04 
AnswerRe: How to simulate press and hold a character key? Pin
BODYPRINT26-Mar-08 0:44
MemberBODYPRINT26-Mar-08 0:44 
GeneralGood article! Pin
valmierietis2-Feb-07 4:04
Membervalmierietis2-Feb-07 4:04 
GeneralRe: Good article! Pin
valmierietis2-Feb-07 4:09
Membervalmierietis2-Feb-07 4:09 
GeneralSend ctrl+alt+del Pin
seralav22-Oct-06 21:48
Memberseralav22-Oct-06 21:48 
GeneralRe: Send ctrl+alt+del Pin
Naren Neelamegam27-Nov-06 18:09
MemberNaren Neelamegam27-Nov-06 18:09 
GeneralRe: Send ctrl+alt+del Pin
MD. Mohiuddin Ahmed12-Dec-12 19:21
MemberMD. Mohiuddin Ahmed12-Dec-12 19:21 
GeneralRe: Send ctrl+alt+del Pin
kero_xmemor2-Apr-13 22:36
Memberkero_xmemor2-Apr-13 22:36 

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