From: "Graeme Fenwick" <gfenwick AT BYESPAMprimex DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Allegro keypressed() always returning False
Date: Thu, 17 Dec 1998 12:39:04 -0000
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

Hi all!

I'm having problems with Allegro's keypressed() function. It seems to be
returning false, regardless of what the user types in.
Leaving it out means the rest of the routine (based around readkey()) works,
but then it pauses every time it needs to scan the keyboard- not brilliant!.
(As a workaround, I suppose I could scan each key individually- not very
elegant though.)
I get the impression the answer would be quite simple- *if* the problem was
caused either by stupidity on my part, or something that isn't obvious from
the docs. Searching the FAQ and Usenet didn't turn up much either, so it
might just be a really lousy error on my part ;-)

Anyway.. here's the program fragment. It's a bit long, but you can ignore
the switch, and all the #defines...

/* Example program only. Alt-Ctrl-End exits. */

#include <stdio.h>
#include <allegro.h>

#define  NO_KEY   0
#define  ONE      1
#define  NONVALID 2
#define  UP       3
#define  DOWN     4
#define  LEFT     5
#define  RIGHT    6
#define  PLUS     7
#define  ENTER    8
#define  SAVE     9

int detect_key(void);

int main(void)
{
   allegro_init();
   install_keyboard();
   while(1)
      printf("%d \n", detect_key());
   return 0;
}


/********** DETECT_KEY: Custom routine only detects relevant keys. Some keys
                        have aliases (e.g. numpad '+' matches '=')
*/

int detect_key(void)
{
   unsigned int   key;

   if (!keypressed());
      return NO_KEY;              /******** PROBLEM HERE!! *** buffer empty?
*/
   key = (unsigned) readkey() >> 8;
   switch (key) {                 /* note alias keys- also, no breaks needed
*/
   case KEY_UP:
   case KEY_8:
      return UP;
   case KEY_DOWN:
   case KEY_2:
      return DOWN;
   case KEY_LEFT:
   case KEY_4:
      return LEFT;
   case KEY_RIGHT:
   case KEY_6:
      return RIGHT;
   case KEY_PLUS_PAD:
   case KEY_EQUALS:
      return PLUS;
   case KEY_1:
      return ONE;
   case KEY_ENTER:
      return ENTER;
   case KEY_S:
   case KEY_SLASH:
      return SAVE;
   default:
      return NONVALID;                               /* nonvalid key pressed
*/
   }
}

--
============================================
Graeme Fenwick   |   gfenwick AT BYESPAMprimex DOT co DOT uk

  "Please remove BYESPAM filter when replying by mail"
                               -- WILLIAM SHAKESPEARE, Hamlet.