Detecting keypress

In a window, how do i detect if an arrow key has been pressed?

[HarryW]

You can either use GetAsynchKeyState to test for it, or (I think) you can trap it in your WindowProc as an event. Probably WM_KEYDOWN or something like that. I'm not too sure about that one.

*Looks in MSDN*

Here it is, WM_KEYDOWN:

WM_KEYDOWN
The WM_KEYDOWN message is posted to the window with the 
keyboard focus when a nonsystem key is pressed. A nonsystem
 key is a key that is pressed when the alt key is not
 pressed. 

WM_KEYDOWN 
nVirtKey = (int) wParam;    // virtual-key code 
lKeyData = lParam;          // key data 
 
Parameters
nVirtKey 
  Value of wParam. Specifies the virtual-key code of the
 nonsystem key. 
lKeyData 
  Value of lParam. Specifies the repeat count, scan code,
 extended-key flag, context code, previous key-state flag,
 and transition-state flag, as shown in the following
 table. 
Value 		Description 
0–15		 Specifies the repeat count for the current 
		message. The value is the number of times the 
		keystroke is auto-repeated as a result of the user 
		holding down the key. If the keystroke is held long 
		enough, multiple messages are sent. However, the 
		repeat count is not cumulative. 
16–23 		Specifies the scan code. The value depends on the 
		original equipment manufacturer (OEM). 
24 		Specifies whether the key is an extended key, such 
		as the right-hand alt and ctrl keys that appear on 
		an enhanced 101- or 102-key keyboard. The value is 
		1 if it is an extended key; otherwise, it is 0. 
25–28 		Reserved; do not use. 
29 		Specifies the context code. The value is always 0 
		for a WM_KEYDOWN message. 
30 		Specifies the previous key state. The value is 1 if 
		the key is down before the message is sent, or it 
		is 0 if the key is up. 
31 		Specifies the transition state. The value is always 
		0 for a WM_KEYDOWN message. 


Return Values
An application should return zero if it processes this message.

[HarryW]

Oh yes, and GetAsynchkeystate:

It's easiest if you define a macro or two which you can then use. Here they are, you don't really need both but you might want them:

#define KEYDOWN(vk_code) ((GetAsyncKeyState(vk_code) & 0x8000) ? 1 : 0)
#define KEYUP(vk_code)   ((GetAsyncKeyState(vk_code) & 0x8000) ? 0 : 1)

You can then use them like this:

if (KEYDOWN(VK_ESCAPE))
   SendMessage(main_window_handle,WM_CLOSE,0,0);