Click here to Skip to main content
15,923,168 members
Articles / Programming Languages / C++

SendKeys in C++

Rate me:
Please Sign up or sign in to vote.
4.87/5 (130 votes)
14 Jun 20046 min read 1.2M   18.3K   164   174
A C++ port and enhancement of C#'s / VB's SendKeys function.


One day I needed to send keys to another application in order to automate a task from my C++ program, but after some research, I found no easy way to do that in C++ and all what was found is reference to VB's or C#'s SendKeys. However, one of the search results returned sndkeys32.pas which is a Delphi code version of the SendKeys() written by Ken Henderson back in 1995.

Since I know Delphi and wanted this same functionality in C++, I decided to port and enhance the code to make it fit my needs. The remainder of the article will explain the concept of sending keys in Win32 and will show you how to use the code in order to send keys in just two lines of code!

Hope you find this article useful.

Key sending concept in Win32

The core functionality of sending keys in CSendKeys revolves around the usage of the keybd_event() Win32 API function.

The keybd_event() produces a keystroke, however the keyboard driver's interrupt handles the calls to this function, which means we can send almost any key combination with less limitations.

In brief, it allows you to send a virtual key, defined in winuser.h as VK_XXX, and a flag which denotes a KeyDown, KeyUp or state to tell if the VKey is an extended key or not.

Normal characters are translated into virtual keys using the VkKeyScan() which takes a CHAR and returns a WORD denoting a VK.

When you send a key, it will be depressed until you send it again with the KEYEVENTF_KEYUP flag.

Here is a small snippet that allows you to send the ALT-TAB sequence:

// press DOWN "Alt-Tab"
keybd_event(VK_MENU, 0, 0, 0);
keybd_event(VK_TAB, 0, 0, 0);


// stop pressing "Alt-Tab"
keybd_event(VK_MENU, 0, KEYEVENTF_KEYUP, 0);
keybd_event(VK_TAB, 0, KEYEVENTF_KEYUP, 0);

As you see, in order to send this simple keys combination, 4 lines of coded were needed. Here is where CSendKeys comes to simplify this task.

How to use the code

In short, the code can be used as:
#include "SendKeys.h"
CSendKeys sk;
// Send "Hello world!"
sk.SendKeys("Hello world!");
// Run notepad


CSendKeys is designed in a way to maintain certain compatibility with C#'s SendKeys while also adding more functionality. So if you used C#'s SendKeys.Send() or VB's before then using CSendKeys becomes easier.

Each key is represented by one or more characters. To specify a single keyboard character, use the character itself. For example, to represent the letter 'a', pass in the string "a" to the method. Naturally to represent a string of characters just pass them in order as "hello".

If you want to send modifier keys such as the SHIFT, ALT, CONTROL or WINKEY keys in addition to normal keys, you might want to use any of the characters defined in Table 3.

For example, if you want to send "A" you usually press Shift+A, which is equivalent to sending these key strokes: "+a" , similarly to send the "~" you would press Shift+` which is equivalent to key strokes "+`" or simply "{TILDE}" (Table 1.b).

All characters in Table 3 are reserved and have special meaning in addition to the left/right parenthesis/braces.

The parenthesis are used to associate a given modifier or modifiers with a group of characters, for example to send the "HELLO", you would describe as "+(hello)" which informs CSendKeys to depress the SHIFT key while sending the following keys group. Whereas the braces are used to enclose any of the keys displayed in Table 1 and 2.

The sent keys are sent to no specific application, instead they are just pressed and whatever application has the keyboard input will take the keys.

In order to send the keys to a specific window/application please use either of the methods:

// 1. activate an application using its handle

// 2. activate an application given its window title

/// 3. activate an application given either or both of its window title/class
sk.AppActivate(NULL, "TheClass"); // NULL means this criteria is not avail

// 4. via SendKeys method
sk.SendKeys("{appactivate Notepad}hello");

The following table is a slightly modified version of the MSDN/SendKeys help:

PRINT SCREEN{PRTSC} (reserved for future use)
Keypad add{ADD}
Keypad subtract{SUBTRACT}
Keypad multiply{MULTIPLY}
Keypad divide{DIVIDE}
(table 1.a)

The following are my additions:

WINKEY{WIN} equivalent to {LWIN}
(table 1.b)

In addition to this, I have added some special keys that act like commands:

Command SyntaxAction
{VKEY X}Sends the VKEY of value X.

Very useful if you don't want to recompile CSendKeys and add new Vkey to the hardcoded special keys table.

For example, {VKEY 13} is equivalent to VK_RETURN.

{BEEP X Y}}Beeps with a frequency of X and a duration of Y milliseconds.
{DELAY X}Delays sending the next key of X milliseconds. After the delaying the following key, the subsequent keys will not be further delayed unless there is a default delay value (see DELAY=X).

Example: {DELAY 1000} <-- delays subsequent key stroke for 1 second.

{DELAY=X}Sets the default delay value to X milliseconds. This will cause every key to be delayed X ms.

If a value is already set and you specify {DELAY Y} you will have your following key delay Y ms but the subsequent keys will be delayed X ms.

Example: {DELAY=1000} <-- all subsequent keys will be delayed for 1 second.

{APPACTIVATE WindowTitle}Activates an application using is WindowTitle.

Very useful if you want to send different keys to different applications.

(table 2)

(table 3)

Here are some examples:

{DELAY=50}@rnotepad~hello world%ha
  1. set delay after each character to 50 ms
  2. WINKEY+R to invoke the run dialog

  3. type "notepad" and press ENTER
  4. Type "hello world"
  5. Invoke Alt+H then press "A" to invoke the about dialog of notepad
{delay=100}{appactivate Calculator}{ESC}5*7~{beep 1000 500}^c{appactivate Notepad}^a{DEL}Result of 5*7 is: ^vGiven that "Calc.exe" and "Notepad.exe" are running:
  1. set delay to 100 ms
  2. activate calculatr
  3. press ESC to clear previous result
  4. type in 5*7 then press ENTER
  5. beep for 500ms with a frequency of 1000
  6. press CTRL+C to copy result
  7. activate notepad
  8. press CTRL+A then DEL in notepad to delete previously written text
  9. type in a phrase then press CTRL+V to paste the copied result
  1. Press NUM,CAPS,SCROll lock in order
  2. Turn them off in reverse order
{DELAY=500}% {DOWN 5}
  1. press ALT+SPACE
  2. press DOWN key 5 times

For more examples see the accompanying sample code.

  • 04/19/2004
    • Initial version development
  • 04/21/2004
    • Added number of times specifier to special keys
    • Added {BEEP X Y}
    • Added {APPACTIVATE WindowTitle}
    • Added CarryDelay() and now delay works properly with all keys
    • Added SetDelay() method
    • Fixed code in AppActivate that allowed to pass both NULL windowTitle/windowClass
  • 05/21/2004
    • Fixed a bug in StringToVKey() that caused the search for RIGHTPAREN to be matched as RIGHT
    • Adjusted code so it compiles w/ VC6
  • 05/24/2004
    • Added Unicode support



This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here

Written By
Web Developer
United States United States
Elias (aka lallousx86, @0xeb) has always been interested in the making of things and their inner workings.

His computer interests include system programming, reverse engineering, writing libraries, tutorials and articles.

In his free time, and apart from researching, his favorite reading topics include: dreams, metaphysics, philosophy, psychology and any other human/mystical science.

Former employee of Microsoft and Hex-Rays (the creators of IDA Pro), was responsible about many debugger plugins, IDAPython project ownership and what not.

Elias currently works as an Anticheat engineer in Blizzard Entertainment.

Elias co-authored 2 books and authored one book:

- Practical Reverse Engineering
- The Antivirus Hacker's Handbook
- The Art of Batch Files Programming

Comments and Discussions

GeneralMy vote of 5 Pin
Garry I 202130-Jan-24 7:04
Garry I 202130-Jan-24 7:04 
QuestionDoes SendKeys work with Unicode characters ? Pin
Member 370923819-May-21 7:43
Member 370923819-May-21 7:43 
QuestionThanks a bunch! Pin
vindy_C29-Nov-17 16:27
vindy_C29-Nov-17 16:27 
QuestionThis is awesome, thanks! Pin
Member 1271875717-Dec-16 12:47
Member 1271875717-Dec-16 12:47 
QuestionAny way to get result after submit ? Pin
Member 1116586713-Jul-15 22:03
Member 1116586713-Jul-15 22:03 
QuestionSend key when screen is locked on Windows 7 Pin
Member 1147900725-Feb-15 2:05
Member 1147900725-Feb-15 2:05 
AnswerRe: Send key when screen is locked on Windows 7 Pin
Elias Bachaalany13-Mar-15 11:12
Elias Bachaalany13-Mar-15 11:12 
QuestionSend key when screen is locked Windows 7 Pin
Member 1147900725-Feb-15 1:57
Member 1147900725-Feb-15 1:57 
QuestionWorking with a Win32 Console Application Pin
Christoph.Jansen@erdonet.de10-Dec-14 1:27
professionalChristoph.Jansen@erdonet.de10-Dec-14 1:27 
AnswerRe: Working with a Win32 Console Application Pin
Elias Bachaalany10-Dec-14 12:59
Elias Bachaalany10-Dec-14 12:59 
Questionlove it Pin
DarkShadowsX58-Dec-14 20:20
DarkShadowsX58-Dec-14 20:20 
AnswerRe: love it Pin
Elias Bachaalany10-Dec-14 20:48
Elias Bachaalany10-Dec-14 20:48 
BugModified binary search method StringToVKey()... Pin
Greg Hellem12-Sep-14 6:15
Greg Hellem12-Sep-14 6:15 
GeneralRe: Modified binary search method StringToVKey()... Pin
Elias Bachaalany11-Oct-14 12:18
Elias Bachaalany11-Oct-14 12:18 
QuestionSelecting a Checkbox Pin
Toby Haddon28-Jun-14 10:54
Toby Haddon28-Jun-14 10:54 
Questiondoesnt work with windows 8 and visual studio 13 Pin
Member 1070395727-Mar-14 3:52
Member 1070395727-Mar-14 3:52 
QuestionUpgrade? Pin
omzig28-Feb-14 5:35
omzig28-Feb-14 5:35 
QuestionIs there a way to do this while keeping windows minimized? Pin
Member 103019681-Oct-13 17:30
Member 103019681-Oct-13 17:30 
AnswerRe: Is there a way to do this while keeping windows minimized? Pin
Elias Bachaalany1-Oct-13 18:33
Elias Bachaalany1-Oct-13 18:33 
AnswerRe: Is there a way to do this while keeping windows minimized? Pin
Hữu Tú Nguyễn7-May-14 22:32
Hữu Tú Nguyễn7-May-14 22:32 
Question#include "SendKeys.h" is getting compilation error Pin
Nodik_08002-Jul-13 0:20
Nodik_08002-Jul-13 0:20 
QuestionI need to know how to open and debug the code in VS2010 Pin
Ahmedn14-Dec-11 3:46
Ahmedn14-Dec-11 3:46 
GeneralIs there any way to use this code with Qt? (error: cannot convert 'const char*' to 'const TCHAR*' ) Pin
gtofighi24-May-11 19:46
gtofighi24-May-11 19:46 
GeneralBugs in CSendKeys::AppActivate(LPCTSTR WindowTitle, LPCTSTR WindowClass) Pin
gregko314618-May-11 4:48
gregko314618-May-11 4:48 
Questionsend ?%$# key event Pin
Member 76917712-Mar-11 23:25
Member 76917712-Mar-11 23:25 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.