man key () - Array of flags indicating key state. Allegro game programming library.
NAME
key - Array of flags indicating key state. Allegro game programming library.
SYNOPSIS
#include <allegro.h>
extern volatile char key[KEY_MAX];
DESCRIPTION
Array of flags indicating the state of each key, ordered by scancode. Wherever possible these values will be updated asynchronously, but if keyboard_needs_poll() returns TRUE, you must manually call poll_keyboard() to update them with the current input state. The scancodes are defined in allegro/keyboard.h as a series of KEY_* constants (and are also listed below). For example, you could write:
if (key[KEY_SPACE])
printf("Space is pressed\n");
Note that the array is supposed to represent which keys are physically held down and which keys are not, so it is semantically read-only.
These are the keyboard scancodes:
KEY_A ... KEY_Z, KEY_0 ... KEY_9, KEY_0_PAD ... KEY_9_PAD, KEY_F1 ... KEY_F12, KEY_ESC, KEY_TILDE, KEY_MINUS, KEY_EQUALS, KEY_BACKSPACE, KEY_TAB, KEY_OPENBRACE, KEY_CLOSEBRACE, KEY_ENTER, KEY_COLON, KEY_QUOTE, KEY_BACKSLASH, KEY_BACKSLASH2, KEY_COMMA, KEY_STOP, KEY_SLASH, KEY_SPACE, KEY_INSERT, KEY_DEL, KEY_HOME, KEY_END, KEY_PGUP, KEY_PGDN, KEY_LEFT, KEY_RIGHT, KEY_UP, KEY_DOWN, KEY_SLASH_PAD, KEY_ASTERISK, KEY_MINUS_PAD, KEY_PLUS_PAD, KEY_DEL_PAD, KEY_ENTER_PAD, KEY_PRTSCR, KEY_PAUSE, KEY_ABNT_C1, KEY_YEN, KEY_KANA, KEY_CONVERT, KEY_NOCONVERT, KEY_AT, KEY_CIRCUMFLEX, KEY_COLON2, KEY_KANJI, KEY_LSHIFT, KEY_RSHIFT, KEY_LCONTROL, KEY_RCONTROL, KEY_ALT, KEY_ALTGR, KEY_LWIN, KEY_RWIN, KEY_MENU, KEY_SCRLOCK, KEY_NUMLOCK, KEY_CAPSLOCK KEY_EQUALS_PAD, KEY_BACKQUOTE, KEY_SEMICOLON, KEY_COMMAND
Finally, you may notice an `odd' behaviour of the KEY_PAUSE key. This key only generates an interrupt when it is pressed, not when it is released. For this reason, Allegro pretends the pause key is a `state' key, which is the only way to make it usable.