C / C++ / MFC

struct MyStruct
{
   int member1;
   int member2;
   int next;
};

// Copyright (C) 2004 Id Software, Inc.

#define idStack( type, next )	idStackTemplate<type, (int)&(((type*)NULL)->next)>

template< class type, int nextOffset >
class idStackTemplate {
public:
	idStackTemplate( void );

	void	Add( type *element );
	type *	Get( void );

private:
	type *	top;
	type *	bottom;
};

#define STACK_NEXT_PTR( element )  (*(type**)(((byte*)element)+nextOffset))

template< class type, int nextOffset >
idStackTemplate<type,nextOffset>::idStackTemplate( void ) {
	top = bottom = NULL;
}

template< class type, int nextOffset >
void idStackTemplate<type,nextOffset>::Add( type *element ) {
	STACK_NEXT_PTR(element) = top;
	top = element;
	if ( !bottom ) {
		bottom = element;
	}
}

// more code.....

<br />
WM_CHAR<br />
The WM_CHAR message is posted to the window with the keyboard focus when a WM_KEYDOWN message is translated by the TranslateMessage function. The WM_CHAR message contains the character code of the key that was pressed. <br />
<br />
A window receives this message through its WindowProc function. <br />
<br />
LRESULT CALLBACK WindowProc(<br />
  HWND hwnd,       // handle to window<br />
  UINT uMsg,       // WM_CHAR<br />
  WPARAM wParam,   // character code (TCHAR)<br />
  LPARAM lParam    // key data<br />
);<br />
Parameters<br />
wParam <br />
Specifies the character code of the key. <br />
lParam <br />
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 <br />
0–15 Specifies the repeat count for the current message. The value is the number of times the keystroke is autorepeated 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. <br />
16–23 Specifies the scan code. The value depends on the original equipment manufacturer (OEM). <br />
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. <br />
25–28 Reserved; do not use. <br />
29 Specifies the context code. The value is 1 if the ALT key is held down while the key is pressed; otherwise, the value is 0. <br />
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. <br />
31 Specifies the transition state. The value is 1 if the key is being released, or it is 0 if the key is being pressed. <br />
<br />
<br />
Return Values<br />
An application should return zero if it processes this message. <br />
<br />
Remarks<br />
The WM_CHAR message uses UTF-16. <br />
<br />
Because there is not necessarily a one-to-one correspondence between keys pressed and character messages generated, the information in the high-order word of the lParam parameter is generally not useful to applications. The information in the high-order word applies only to the most recent WM_KEYDOWN message that precedes the posting of the WM_CHAR message. <br />
<br />
For enhanced 101- and 102-key keyboards, extended keys are the right ALT and the right CTRL keys on the main section of the keyboard; the INS, DEL, HOME, END, PAGE UP, PAGE DOWN and arrow keys in the clusters to the left of the numeric keypad; and the divide (/) and ENTER keys in the numeric keypad. Some other keyboards may support the extended-key bit in the lParam parameter<br />
<br />