MOMOP'S GUIDE TO PERFECT DEBUGGING!!!
This is not really a tuturial so much as a guide. Don't you hate when you have written out a 1000 some odd program and it won't run or not how you want it too?
If you answered no then you can leave as this guide will not help you however if you answered yes then your normal
On to the guide
We will attempt to move a circle using the keyboard
now on to moving a circle!!!!!!!
| Turing: |
%The program that doesnt not run
%created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar,offscreenonly") %some movement varibles var circlex, circley : int var key : array char of boolean %draw your circle drawfilloval (circlex, circley, 25, 25, red) %now to set these varibles circlex := 150 circley := 150 %and so on loop %allow the user to move circle Input.KeyDown (key) if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if end loop |
well that didnt work why not?
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varible has no value |
well thats not good we set the varible but turing is not reading it let's check over the program
well first of all we did set the circlex and circley varibles
then we drew the circle
then we set the varibles
and thats where the answer lies...
we drew the circle before we set the varibles lets reverse that
| Turing: |
%The program that doesnt not run %created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar,offscreenonly") %some movement varibles var circlex, circley : int var key : array char of boolean %now to set these varibles circlex := 150 circley := 150 %draw your circle drawfilloval (circlex, circley, 25, 25, red) %and so on loop %allow the user to move circle Input.KeyDown (key) if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if end loop |
woot it runs!!!!
but wait I can't move the circle what's up wit dat yo?
lets review once more
we set the varibles
we set the varibles
we drew the circle
we created the main loop which houses the movement commands
once more we have found the answer!!!!!
we drew our circle before our loop so lets rewrite our program once more!!!!
| Turing: |
%The program that doesnt not run %created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar,offscreenonly") %some movement varibles var circlex, circley : int var key : array char of boolean %now to set these varibles circlex := 150 circley := 150 %and so on loop %draw your circle drawfilloval (circlex, circley, 25, 25, red) %allow the user to move circle Input.KeyDown (key) if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if end loop |
well it's still not working lets review once more *sigh*
we set our varibles, we created our loop with the draw command inside, this is a debugging guide and doesn't get into movement commands so thats not it, it must be something else
at the top where the program says it's just looking fancy... it's not, its also limiting movement with the "offscreenonly"
so what now? just erase it?
lets try
| Turing: |
%The program that doesnt not run %created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar") %some movement varibles var circlex, circley : int var key : array char of boolean %now to set these varibles circlex := 150 circley := 150 %and so on loop %draw your circle drawfilloval (circlex, circley, 25, 25, red) %allow the user to move circle Input.KeyDown (key) if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if end loop |
...well atleast it's working...
as you just saw the circle is moving too fast so lets slow it down a bit... you guessed it the delay([milliseconds]) command!!!
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%The program that doesnt not run %created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar") %some movement varibles var circlex, circley : int var key : array char of boolean %now to set these varibles circlex := 150 circley := 150 %and so on loop %draw your circle drawfilloval (circlex, circley, 25, 25, red) %allow the user to move circle Input.KeyDown (key) if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if delay(1000) end loop |
woot its working!!!!!... but not perfectly...
did you notice if you hold a direction the ball will keep moving after you've let go?
well lets fix that
but first an explanation of what is happening
when you press a key the program reads it and sets it in a line so if i hit the 'w' key the program would read:
w
however if i held the key 'w' the program would read:
wwwwwwwwwwwwwwwwwwww
each time the Input.KeyDown is reached it will knock off one key so:
wwwwwwwwwwwwwwwwwww
wwwwwwwwwwwwwwwwww
wwwwwwwwwwwwwwwww
wwwwwwwwwwwwwwww
wwwwwwwwwwwwwww
wwwwwwwwwwwwww
and so on
if i hit 'w' and 'd' then:
wd
d
or if I hit 'w' 'd' 's' and 'a' then:
wdsa
dsa
sa
a
but if I do not want this then i use the Input.Flush command
so if I had a prgram running like
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and I had typed wwwwwwww beforehand then:
wwwwwwwwww
wwwwwwwww
*nothing*
the third Input.KeyDown did not receice any keys because the Input.Flush got rid of them or flushed em down the toilet
so back to the program
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%The program that doesnt not run %created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar") %some movement varibles var circlex, circley : int var key : array char of boolean %now to set these varibles circlex := 150 circley := 150 %and so on loop %draw your circle drawfilloval (circlex, circley, 25, 25, red) %allow the user to move circle Input.KeyDown (key) Input.Flush if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if delay(500) end loop |
thats much better!!! (ps you can lower the delay i had it higher to show the effects of Input stocking)
but not quite perfect... ya this is kinda repetitive but bear with me...
the circle leaves a trail, well ill take care off that...
the cls command is our friend this time
but there are 2 solutions to this...
either use the cls everytime a key is pressed or each loop run lets try both:
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or
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loop cls %draw your circle drawfilloval (circlex, circley, 25, 25, red) %allow the user to move circle Input.KeyDown (key) Input.Flush if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if delay(500) end loop |
both ways work but for further work we'll stick to using cls each loop run for this program
i bet you've noticed the circle was flashing... didn't ya... did ya cause i did... i really did
anyway there is a way around this flashing and thats to bring back the "offscreenonly" but with his friend View.Update
heres how this works
offscreenonly draws all images off the screen which is why the circle did not move... it actually did just not on screen so you didn't see it move
whenever the View.Update command is used turing brings all images from offscreen onto the onscreen
| Turing: |
%The program that doesnt not run %created by: Nick Hearn aka momop %23-aug-07 %not too important just making program look nice setscreen ("graphics:500;400,nobuttonbar,offscreenonly") %some movement varibles var circlex, circley : int var key : array char of boolean %now to set these varibles circlex := 150 circley := 150 %and so on loop %clear the screen to erase any trials cls %draw your circle drawfilloval (circlex, circley, 25, 25, red) %move the circle onscreen View.Update %allow the user to move circle Input.KeyDown (key) Input.Flush if key ('w') then circley += 5 elsif key ('s') then circley -= 5 elsif key ('a') then circlex -= 5 elsif key ('d') then circlex += 5 end if delay (500) end loop |
wow that seems perfect... not quite but almost there!!!!
if you pressed two keys at once you noticed the circle ignored one movement
thats because in an if statement once one requirement has been met it ignores all other elsif's and else's so what to do?
break up the if statement like so
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if key ('w') then
circley += 5 end if if key ('s') then circley -= 5 end if if key ('a') then circlex -= 5 end if if key ('d') then circlex += 5 end if |
AND YOU'RE DONE we have just successfully debugged this program!!!!
but these arent the only ways to debug a program
heres some tips:
1)use put... put can also output varibles
use this if a varible is acting weird to help find the problem an example from our circle program would be
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put circlex |
2)the break command... this will pause the program until the user hits the resume button on the button bar
use this to stop the program at any location to see what is happening
3) the assert command
this works like put but not in the same way
if a varible is acting strange and not how you want use assert to make sure the varible is what you want
the assert command will stop the program if a varible does not meet the assert requirements hence showing you where the problem is
an example:
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assert [var name] (>,>=,=,<=,<,not) [same argument type as [var name]]
so... assert circlex>100 |
4)the debugger menu... to open this menu click on run at the very top of the turing window (not your programs run window as there is no run there)
be sure to click on the correct run as there are two the right one is above the other and slighty right to it
this should open a dropdown menu just click on show debygger menu from here and enjoy
well thats it thanks for your time
if there are any errors please PM me also note that some examples are not meant to run which is the point
have fun and never once again be frusterated at your program for not running
ill be sure to use proper tags headings and grammer in the future 