qbasic programing

 BBS: Inland Empire Archive
Date: 04-20-92 (05:26)             Number: 186
From: MIKE PHILLIPS                Refer#: NONE
  To: ANTHONY CORSA                 Recvd: NO  
Subj: qbasic programing              Conf: (3) Dr_Debug

 AC> I am teaching my self to program in qbasic but There
 AC> was no book that came with it when I bought my
 AC> computor with dos 5.0.
 AC> There is a help file but I can not figure out how to grab a char
 AC> and move it around with the arrow keys. I think I'm
 AC> suppose to use the GET and PUT funtions but I'm not
 AC> sure.

    The GET statement (in graphics application) snags a rectangle of screen
and stores it into an array (memory).  The PUT statement
displays the captured image at a specific location on the
screen.
    In order to cause the image to move at a keypress, you
must XOR the image on the screen (reverses all the bits,
making the image disappear,without impacting the
background, if done correctly, i.e. the first XOR
incorporates the image into the existing background.  A
second XOR erases the image, leaving the screen area just
as it was before the first XOR.
    Once you have figured out how to move an image on the screen, then you
merely develop a CASE SELECT construct to identify which
key is being pressed, and move the image dependent upon the
user input.  You have to trap for keys using scan codes
(the help has a list of possibilities).
    For coding examples, please join us in the QUIK_BAS echo (available to
you here on your first call) where 'real' experts are
gathered, or download the QuickBASIC News (available to you
here on your first call) which has tremendous teaching
tools incorporated (some of which are only for QuickBASIC
and not for Qbasic (the former includes a compiler, the
latter is bundled with DOS).
    There are also some good second party books for
QuickBASIC which will help you enormously.  I hope this has
been of some help.  I don't have any coding examples that
move a character based on a key press, but I hope I have
given you a clue.


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