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GetAsyncKeyState( )

Started by VoytekG Jun 15, 2002 at 3:14 PM 10 replies 1.2k views

Original Post

Jun 15, 2002 at 3:14 PM

Hey! Can someone help me out with the GetAsyncKeyState() function? I know that you can use it for buttons like the escape buttom, which is VK_ESCAPE. That''s what I have in my program: if (GetAsyncKeyState(VK_ESCAPE)) { MessageBox(NULL, "Bye", "Exit", MB_OK); PostQuitMessage(0); } I was just wondering if it''s possible for me to use this function to get other keyboard buttons (is there a list, maybe?). I tried to use regular Ascii numbers. "d" is 100 for example, but when I put an if (GetAsyncKeyState(100)) it never returned true, always false. Does anyone know how I can make it recognize those keys? Or would I have to put it in the WndProc() function? Thanks, Voytek

intransigent-seal

Jun 15, 2002 at 3:21 PM

There should be a list of the "Virtual Key" constants (all beginning with VK_ like VK_ESCAPE) in help, or on MSDN.

As far as I know, they''re just scancode values (ie based on the position on the keyboard, not the position in the ASCII set).

Normal ones are VK_SPACE, VK_A to VK_Z etc.

John B

VoytekG

Jun 15, 2002 at 4:06 PM

Hey!
When I put VK_A it gives me an error saying "Undeclared Identifier". I found a list on MSDN with the different VK_ values, but none of them deal with letters, only special keys on the keyboard.
Thanks,
Voytek

Chem0sh

Jun 15, 2002 at 5:15 PM

For some strange reason, VK_A to VK_Z are not defined (neither are VK_0 to VK_9). You have to define them yourself. Search on MSDN for "virtual key codes". That will give you a list of all of the codes in hex. The simplist way to define them is to use an enumeration:


enum { VK_A = /*whatever the hex value is*/, VK_B, VK_C, //etc };

Anyone know why they aren''t already defined?

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superpig

Jun 15, 2002 at 5:19 PM

Aren''t they in some other, weird header file?

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Chem0sh

Jun 15, 2002 at 5:22 PM

I don''t know. I''ve never seen it. It would be nice if they were so I wouldn''t have to go around defining them all the time.

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Thunder_Hawk

Jun 15, 2002 at 5:25 PM

I read a post in one of the forums the other day that said that VK_A and such were only for Windows CE, anyways can''t you just go GetAsyncKeyState(''d'')? (that really aught to be the same as using 100...hmmm)

Hope that helps a bit

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Chem0sh

Jun 15, 2002 at 5:35 PM

No, Thunder_Hawk, you can''t use ''d'' because virtual key codes are scan codes, not ascii codes. scan codes != ascii.

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zealouselixir

Jun 15, 2002 at 5:52 PM

Actually, you can use ASCII codes with GetAsyncKeyState. However, they have to be the upper-case equivalents of the keys you want to check, e.g.

(GetAsyncKeyState(''A'') & 0x8000) ? true : false

will evaluate to true if the A key is pressed.

I personally define all the alphanumeric key constants in a header file.

Later,
ZE.

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Chem0sh

Jun 15, 2002 at 7:40 PM

[edited by - Chem0sh on June 17, 2002 11:02:44 PM]

Promit

Jun 15, 2002 at 10:07 PM

quote:
winuser.h
]/* VK_0 thru VK_9 are the same as ASCII ''0'' thru ''9'' (0x30 - 0x39) */
/* VK_A thru VK_Z are the same as ASCII ''A'' thru ''Z'' (0x41 - 0x5A) */

Would it really have killed you to read the header?

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