Re: Delete key issue...

["Bill Buckels" <bbuckels@mts.net>]

"Harry Potter" <rose.joseph12@yahoo.com> wrote:

> the backspace key acts as a left cursor key.  Any idea on why?  And how to 
> fix it?

/* keypress values for the apple */

#define RTARROW  21
#define LTARROW  8
#define UPARROW  11
#define DNARROW  10
#define ESCAPE   27
#define DELETE   127
#define ENTERKEY 13
#define SPACEBAR 32

The ascii value for the backspace key whether one writes code for the Apple 
II or MS-DOS is 8.

The fix is to forget about writing code for the Apple II and focus your 
efforts on code for some other platform:

/* arrow keypress values for the commodore 64 */

#define UP_ARROW      145
#define DOWN_ARROW   17
#define LEFT_ARROW   157
#define RIGHT_ARROW   29

MS-DOS arrow keys might be a little trickier for you in a C program... so 
staying away from C altogether and writing in QuickBASIC for MS-DOS might be 
a better alternative:

'constants for keypress values
NUL$ = CHR$(0)
UP$ = NUL$ + CHR$(72)
DN$ = NUL$ + CHR$(80)
LT$ = NUL$ + CHR$(75)
RT$ = NUL$ + CHR$(77)
ESC$ = CHR$(27)
ENTER$ = CHR$(13)

 FLAG = 0

WHILE FLAG = 0
  KEYPRESS$ = INKEY$
  SELECT CASE KEYPRESS$
    CASE UP$ 'uparrow
    CASE DN$  'down arrow
    CASE LT$  'left arrow
    CASE RT$  'right arrow
    CASE ESC$
        FLAG = 1
    CASE ENTER$
        FLAG=1
    END SELECT

I think arrow keys in a message loop in a Windows C Program would be very 
hard for you to manage so I have refrained from posting an example.

> I am willing to post the code online--

No need to go to all that work... but thanks for the offer.

Here's some code (bottom of page) that may help you understand a little 
better... it's in Aztec C65 but any C programmer (and I mean ANY C 
programmer) would have no trouble porting this code to another Apple II C 
compiler... clue - consider using cc65's  functions to replace mine (this 
might work for you, who knows):

while (kbhit() == 0);
 c = cgetc();

You may use this code for whatever you wish as long as you agree that Bill 
Buckels has no warranty or liability obligations whatsoever from said use.

/* return ascii values for apple key presses */

#include <stdio.h>

int getch()
{
char *KEYPRESS = (char*)0xC000;
char *KEYCLEAR = (char*)0xC010;
char c;
/* clear stragglers from the keyboard buffer */
while((c=KEYPRESS[0]) > 127)KEYCLEAR[0]=0;

/* read the keyboard buffer */
/* and return the character */
do{
   c = KEYPRESS[0];
   }while(c < 128);

   c-=128;
   KEYCLEAR[0]=0;
   return (int )c;
}

main()
{
int c=0;

scr_clear();
while(c!=27)
{
printf("Press a Key : \n");
c=getch();
printf("Key = \"%c\". Ascii = %d.\n",(char)c,c);

}
scr_clear();
_exit(0);

}

- Bill