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Posted 28 Apr 2002

Beginner's Tutorial - Using global hotkeys

, 28 Apr 2002
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Explains how to register, use and unregister hotkeys


Today morning, someone was asking about using hot keys in the VC++ forum. I had never used hotkeys and it intrigued me not a little. I thought I'd cook up a simple application and write a nice little article for CP. These days I have been writing too many .NET articles and I thought it's time I wrote a normal unmanaged program as Mike Dunn or Colin Davies would call it.

First of all remember that hot keys are going to be global to the Operating System. Thus be careful what you choose as your hot key. Also decide whether your application is important enough to have an Operating System level short cut key. The user might accidentally press Ctrl-D and suddenly find your program popping up. In fact if it's an old enough person the sudden popping up of an unexpected window might even give him or her a heart attack. This is obviously a situation to be avoided.

How to set hot keys

Well, setting hot keys is just an API call away for anyone who might be thinking it's a complicated process. We use the API call RegisterHotKey which is prototyped as follows.

BOOL RegisterHotKey(
    HWND hWnd,         // window to receive hot-key notification
    int id,            // identifier of hot key
    UINT fsModifiers,  // key-modifier flags
    UINT vk            // virtual-key code

A normal application can use any value between 0x0000 and 0xBFFF but if you are writing a DLL, then you must use GlobalAddAtom to get a unique identifier for your hot key. There are currently four allowed key modifiers which let you trap the Ctrl key, the Alt key, the Shift key and the WinKey. You may trap them individually or as combinations of each other. For example you can have a combination short cut like Ctrl-Shift-WinKey-Y to pop up yahoo messenger, though why you'd want to set up that kind of convoluted short cut would be a very tough question to answer.

RegisterHotKey(hWndA, 100, MOD_ALT | MOD_SHIFT, 'P');
RegisterHotKey(hWndA, 200, MOD_WIN, 'R');

Okay, setting the hot key was simple. So, what does this do? Good question! What we have achieved is that, whenever this hot key is pressed a WM_HOTKEY message is send to the window specified by the HWND parameter. Neat. Also remember that if you are trying to set a hot key that has already been registered like the WinKey-E hot key that brings up Explorer, this function will fail and return FALSE, else it will return TRUE. So please do not fail to check the return value.

Un-registering hotkeys

Well as you would expect, there is an API call called UnregisterHotKey which un-registers our hot key or hot keys. Remember to un-register all hot keys when your program exits. In fact just to be safe un-register a key which might actually already have been un-registered. No harm done at all. This function is prototyped as :-

BOOL UnregisterHotKey(
    HWND hWnd,  // window associated with hot key
    int id      // identifier of hot key

The identifier is the same one which we had passed to RegisterHotKey. If you had used GlobalAddAtom to get a unique identifier, you must save it somewhere so that you can use it to un-register the hot key.


Handling the hot key

If you are writing a straight API program you shouldn't have too much difficulty in handling the WM_HOTKEY message. Just check wParam which will contain the identifier of the hot key. The problem with MFC is that for some strange reason, the class wizard does not seem to include the WM_HOTKEY message. I was using VC++ 6.0 with SP5 when i originally wrote the program. I am not aware of whether this is the same for VC++ 7.0 or even whether there is some kind of obscure workaround for VC++ 6.0. If anyone knows a work around, kindly let me know too. But there is nothing stopping us from adding the entry to the message map. It's perfectly within the rules to do that, I say.


Okay, that was easy. Now we add our function. Just add this function to your window class, the same window that is going to receive the WM_HOTKEY message.


Now all you have to do is to write the function body, check wParam and see if it is the identifier of your hot key and do what you want. Typically you might want to use ShellExecute to start your program, which is what I have done in the sample program for this article.

Sample Program

Well. the sample program was quickly put together and it lets you choose a single modifier key (it does not allow multiple modifiers) and you can choose a virtual key between A and Z. You can also browse to an executable and when you click the Start button, the hot key is alive. It's a very simple program and does not really do much. But you can look through the source code, if my explanations weren't coherent enough for you.


This article, along with any associated source code and files, is licensed under The Microsoft Public License (Ms-PL)


About the Author

Nish Nishant
United States United States
Nish Nishant is the Principal Software Architect/Consultant for Ganymede Software Solutions LLC, and is based out of Columbus, Ohio. He has over 17 years of software industry experience in various roles including Lead Software Architect, Principal Software Engineer, and Product Manager. Nish was a Microsoft Visual C++ MVP between 2002 and 2015.

Nish is an industry acknowledged expert in the Microsoft technology stack. He authored C++/CLI in Action for Manning Publications in 2005, and had previously co-authored Extending MFC Applications with the .NET Framework for Addison Wesley in 2003. In addition, he has over 140 published technology articles on and another 250+ blog articles on his WordPress blog. Nish is vastly experienced in team management, mentoring teams, and directing all stages of software development.

Contact Nish : If you are interested in hiring Nish as a consultant, you can reach him via his google email id voidnish.

Company Website :

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Comments and Discussions

QuestionHow do a system wide hot key in C# Pin
pschiff3-May-04 12:27
memberpschiff3-May-04 12:27 
AnswerRe: How do a system wide hot key in C# Pin
Jigar M25-Apr-08 12:36
memberJigar M25-Apr-08 12:36 
GeneralHotkey functionality in Win 9X family Pin
Antti Keskinen28-Oct-03 3:10
memberAntti Keskinen28-Oct-03 3:10 
Generalhot keys & mouse button virtual keys Pin
ducl_1315-Apr-03 21:40
memberducl_1315-Apr-03 21:40 
GeneralRe: hot keys & mouse button virtual keys Pin
Nishant S19-Apr-03 20:55
editorNishant S19-Apr-03 20:55 
QuestionSkip fsModifiers? Pin
Gopalan9-Feb-03 4:18
memberGopalan9-Feb-03 4:18 
AnswerRe: Skip fsModifiers? Pin
Nishant S9-Feb-03 6:01
editorNishant S9-Feb-03 6:01 
GeneralMultiple Hotkey Pin
eponk30-Dec-02 2:05
membereponk30-Dec-02 2:05 
I want to have multiple hotkey?
How to trap them ?
Is it in lParam? how?
GeneralRe: Multiple Hotkey Pin
Nishant S9-Feb-03 6:02
editorNishant S9-Feb-03 6:02 
QuestionHow to send keystrokes to another window in OnHotKey()? Pin
xyu25-Aug-02 21:05
memberxyu25-Aug-02 21:05 
AnswerRe: How to send keystrokes to another window in OnHotKey()? Pin
Nishant S26-Aug-02 0:09
editorNishant S26-Aug-02 0:09 
GeneralQuestion... Pin
J.G. Hattingh29-May-02 1:03
memberJ.G. Hattingh29-May-02 1:03 
GeneralRe: Question... Pin
Nish - Native CPian29-May-02 1:41
memberNish - Native CPian29-May-02 1:41 
GeneralGood article Pin
tdi29-Apr-02 10:36
membertdi29-Apr-02 10:36 
GeneralRe: Good article Pin
Nish [BusterBoy]29-Apr-02 14:59
memberNish [BusterBoy]29-Apr-02 14:59 
GeneralRe: Good article Pin
Daniel Turini29-Apr-02 21:44
memberDaniel Turini29-Apr-02 21:44 
GeneralRe: Good article Pin
Nish [BusterBoy]30-Apr-02 8:45
memberNish [BusterBoy]30-Apr-02 8:45 
GeneralRe: Good article Pin
Philippe Lhoste10-May-02 5:29
memberPhilippe Lhoste10-May-02 5:29 
GeneralRe: Good article Pin
Anonymous30-May-02 15:55
memberAnonymous30-May-02 15:55 
QuestionPink? Pin
Jonny Newman29-Apr-02 10:17
memberJonny Newman29-Apr-02 10:17 
AnswerRe: Pink? Pin
Nish [BusterBoy]29-Apr-02 14:58
memberNish [BusterBoy]29-Apr-02 14:58 
GeneralRe: Pink? Pin
Jonny Newman30-Apr-02 8:33
memberJonny Newman30-Apr-02 8:33 
GeneralRe: Pink? Pin
Nish [BusterBoy]30-Apr-02 8:44
memberNish [BusterBoy]30-Apr-02 8:44 
GeneralRe: Pink? Pin
Jonny Newman30-Apr-02 8:49
memberJonny Newman30-Apr-02 8:49 
GeneralRe: Pink? Pin
Nish [BusterBoy]30-Apr-02 8:55
memberNish [BusterBoy]30-Apr-02 8:55 

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