Floppyshop 2/Floppyshop - 2.zip/Floppyshop - 2.iso/diskmags/3565-4.665/dmg-4385/issue_10/17.pne

Text File | 1987-04-21 | 6KB | 124 lines

                       WRITING A PROGRAM IN STOS

                          ARTICLE BY DEANO

   Well you've opened the STOS manual.  You've read it and seen all  the
   clever  commands and accessories you can use.  You've read and  heard
   that all this can enable you to write your very own masterpiece.

   But  how do you start,  what do you do,  how do you tell STOS  to  do
   this.....this  are  the questions the beginner  asks.  Well  in  this
   article I'm going to waffle on about the subject of writing your  own
   pieces of code. And show you how to write a simple game.

   First......how  do  we start?  Well....first we need  to  learn  some
   commands.  A program is just a group of commands that tell STOS  what
   to do. We start off with simple commands and we type out the examples
   in the STOS manual.  This helps to give us a good idea of  commanding
   STOS and telling it what to do.

   Lets  say  we wanted STOS to print something on the screen  over  and
   over again. We can use the PRINT and GOTO commands like this...

   10 print"STOSSER"
   20 goto 10

   Here we have a simple program.  First it prints the word STOSSER onto
   the screen, and then it goes onto the next line that tells STOS to go
   back to line 10 and print STOSSER on the screen again.

   So  as you can see,  we have grouped two commands together to make  a
   small program.....actually a small program like this is better  known
   as  a  routine.  A program such as a game is just a  large  group  of
   routines. Lets try a routine that counts up to ten.

   10 for X=1 to 10
   20 home:print X:wait 5
   30 next X

   What we have here is a loop that adds one to the varible X, prints it
   one  the screen,  then stops when X reaches 10.  The HOME command  is
   used to tell STOS to keep the counter to the same part of the screen,
   and the WAIT command stops STOS from printing too fast.

   So.....once  we  have learnt the commands we can  easily  group  them
   together.  Once you've been learning them,  typing out examples,  and
   looking at other routines, you'll find it all comes clearer.

   Lets program a small game.  First we have to decide what the  program
   is going to be, and what it does. The game in question is a Guess the
   Number  game where STOS will first choose a random number,  then  ask
   the player to guess it.  If the players guess is wrong then STOS will
   tell him so. First....lets set up the screen.

   10 key off : hide : mode 0

   Next we can put the games name up, known as the title screen.

   20 locate 0,1 : centre"NUMBER GUESSER"

   Now we need to tell STOS to choose a random number, like this.

   30 RN=rnd(10) : if RN=0 then goto 30

   This line will choose a different number from 1 to 10 every time STOS
   comes  across  it.  With  programming we  are  sometimes  faced  with
   problems,  in this case, the RND command will sometimes choose nought
   as a random number.  The problem is that we only want numbers from  1
   to 10.  So therefore we add an IF THEN statement to tell STOS that if
   it chooses nought....then go back and try again.

   When STOS has chosen a number between 1 and 10,  it needs to ask  the
   player to guess the number.

   40 locate 2,4 : print"I am thinking of a number between 1 and 10"
   50 locate 2,5 : print"Can you guess what it is?"

   Next we need a way of letting the player entering his guess.

   60 input A

   This command waits for the player to enter a number and press return.
   Now  so  far  we have the RN varible which holds  the  random  number
   chose by the game, and the A varible which holds the number chosen by
   the player. But what if the player has typed in a number which is out
   of range......we can check for this with these two lines.

   70 if A<1 then print"Your guess is too low, try again" : goto 60
   80 if A>10 then print"Your guess is too high, try again" : goto 60

   So  if  the  number in the A varible is out of range  then  the  game
   imforms  the player to try again then goes back to the input at  line
   60.  Now we need a line to check if the player has  guessed the right
   number........like so.

   90 if A<>RN then print"Thats not it, try again" : goto 60

   This  line  checks if the A varible contains the same number  as  the
   varible chose by the game.  Here we are telling the game that if  the
   players  guess is other than the number the game has chosen  then  to
   give them a chance to try again.

   Finally we need to check if the player has guessed the right number.

   100 if A=RN then print"Well done, you've guessed the number" : stop

   So  there  we  have it.  A small game produced by  just  a  group  of
   routines.  We can easily improve it, such as getting the game to loop
   back  to the start after the player wins.  We could also  add  extras
   such as a score by simply adding points to a varible and printing  it
   on the screen like this.

   110 SC=SC+10 : print"Your score is now:";SC
   120 wait 50 : cls : goto 20

   If you are just starting on programming.  Then you will be pleased to
   know that there is a book to help you. Its called The Beginners Guide
   to STOS and you can get it from MT SOFTWARE. Another good book is the
   Game Makers Manual also from MT SOFTWARE.

   This is DEANO signing off...........