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| Apple IIc programming confusion |
Posted by: Apostrophe on 2009-02-24 16:20:33
Hi,
If you haven't already seen my post in Conquests, one of the power supplies I ordered for my Apple IIc has just arrived, and I played with the IIc for about two hours. It works great! And I've been getting better at programming it.
But there's one thing I can't get it to do. I've mastered Graphics mode; I successfully plotted a smiley face (and altered its colors), I successfully got it to run number/variable related programs I write for it, I have more or less mastered commands like HOME, RUN, LIST, PRINT, INPUT, NEW, END, IF...THEN, GOTO, etc. But I can't get it to accept text answers.
If I write a program telling it to ask me the year, it works fine. For instance, here's the program I wrote, along with the result:
new
10 home
20 input "What year is it?";a
30 if a="2009" then goto 50
40 if a<>"2009" then goto 10
50 print "Correct!"
60 end
run
What year is it? 2009
Correct!
But I can't get it to do the same with words. For instance, I want it to ask for the state I live in (Ohio) and then ask for the month (February). But the result isn't quite as favorable. I've tried various combinations of string variable techniques as well, to no avail. Below is my program, along with the result:
new
10 home
20 input "What state do you live in?";a
30 if a="Ohio" then goto 50
40 if a<>"Ohio" then goto 10
50 input "Correct! Type 'next' for the next question.";b
60 if b="next" then goto 70
70 home
80 input "What month is this?";c
90 if c="February" then goto 110
100 if c<>"February" then goto 70
110 print "Correct! Thus concludes this program."
120 end
run
What state do you live in?Ohio
?REENTER
What state do you live in?OHIO
?REENTER
What state do you live in?"Ohio"
?REENTER
What state do you live in?Ohio$
?REENTER
What state do you live in?"Ohio$"
As you can see, I've tried various combinations of Ohio, all with no results. And sometimes, it does this:
...
...
110 print "Correct! Thus concludes this program."
120 end
run
?SYNTAX ERROR IN 3
And so I'd type LIST 30, but the line looks just as I typed it, with no obvious mistakes.
So then I'd try to skip it. I'd type RUN 70, and it asks the question at 70, but never accepts my answer as the correct one, saying ?REENTER What month is this? over and over and over again, no matter what I type in.
Is there something I'm missing? Anything I'm not doing quite right?
-Apostrophe
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Posted by: wally on 2009-02-24 16:49:16
Try using a$ where you were using a.
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Posted by: Apostrophe on 2009-02-24 16:51:20
I've already tried that, actually. No results. 🙁
-Apostrophe
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Posted by: david__schmidt on 2009-02-24 17:12:34
You need all string variables.
10 home
20 input "What state do you live in?";a$
30 if a$="Ohio" then goto 50
40 if a$<>"Ohio" then goto 10
50 input "Correct! Type 'next' for the next question.";b$
60 if b$="next" then goto 70
70 home
80 input "What month is this?";c$
90 if c$="February" then goto 110
100 if c$<>"February" then goto 70
110 print "Correct! Thus concludes this program."
120 end You'll probably be happier with ALL CAPS, too. 🙂
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Posted by: Apostrophe on 2009-02-24 17:18:22
Thanks David--as I told wally, I've already tried string variables, but maybe I didn't do it right, or missed a few keys, etc.
When I turn the IIc on again tomorrow I'll try entering the revised code you provided, David. I'll let you know how it turns out. 🙂
-Apostrophe
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Posted by: wally on 2009-02-24 17:20:25
Just a guess...you may have to declare a$ first specifying a non zero maximum string length in bytes.
Try
Dim A$(64), B$(64), C$(255)
at the start of the program and see if that gives you some string variables of non zero length to play with.
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Posted by: Apostrophe on 2009-02-24 17:25:55
Okay. Thanks wally! I'll try that.
-Apostrophe
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Posted by: wally on 2009-02-24 18:15:03
My prior post may go too far and create arrays of string variables, so also try the simpler
DIM A$(1), B$(1), C$(1) or even simpler DIM A$, B$, C$
I saw somewhere that Applesoft Basic went to dynamic garbage collection for variable length strings (and if so length was automatic up to some large number of bytes), but have yet to find a reference manual or program example clarifying declaration requirements and rules. In Atari Basic the DIM A$(64) was needed and just created a single string variable holding up to 64 bytes as an example.
Further edited post:
If on your IIc you are using Applesoft BASIC
http://apple2.info/wiki/index.php?title=Applesoft_BASIC#String_expressions_and_Assignments
has some reference info. I get the impression that string variables are dynamically declared and only string arrays need declarations, and that the example by david__schmidt should work without a DIM statement (but what do I know!). Upperlower case may create some issues too.
http://knowledgerush.com/kr/encyclopedia/Applesoft_BASIC_programming_language/
has some historical info on the shift from Integer Basic to Applesoft Basic.
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Posted by: luddite on 2009-02-24 19:31:01
DIM A$(1), B$(1), C$(1) or even simpler DIM A$, B$, C$ Neither is necessary... the first will create arrays and the second AFAIK won't do anything. Simply changing the variable to string variables works just fine
10 HOME
20 INPUT "What state do you live in?";A$
30 IF A$ = "Ohio" THEN GOTO 50
40 IF A$ < > "Ohio" THEN GOTO 10
50 INPUT "Correct! Type 'next' for the next question.";B$
60 IF B$ = "next" THEN GOTO 70
70 HOME
80 INPUT "What month is this?";C$
90 IF C$ = "February" THEN GOTO 110
100 IF C$ < > "February" THEN GOTO 70
110 PRINT "Correct! Thus concludes this program."
120 END Edit: If I was paying attention I might have noticed that Dave Schmidt already corrected the program... so much work for nothing! ;-)
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Posted by: wally on 2009-02-25 09:17:50
Not having an Apple IIc handy but wanting the experience I went to http://www.calormen.com/Applesoft/index.htm and tried out the Applesoft Basic simulator that runs in Javascript. As others had said, no pre dimensioning/declaration of string variables necessary. Unless I am operating this simulator incorrectly, you can input statements including strings to be compared in mixed upper lower case, but the keyboard input received in input statements is upshifted to all caps. So your tests of any sting loaded from an input statement should read if a$ = "STRINGINALLCAPS" otherwise the comparison fails. You can still PRINT "UPPERlowercase" and that displays both cases. Acts like my keyboard is stuck on caps for input statements only.
10 home
20 input "What state do you live in?";a$
30 if a$="OHIO" then goto 50
40 goto 10
50 input "Correct! Type 'next' for the next question.";b$
60 if b$="NEXT" then goto 70
62 home
63 input "Type 'next' for the next question.";b$
65 goto 60
70 home
80 input "What month is this?";c$
90 if c$="FEBRUARY" then goto 110
100 goto 70
110 print "Correct! Thus concludes this program."
115 stop
120 end
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Posted by: Dog Cow on 2009-02-25 10:38:59
new
10 home
20 input "What state do you live in?";a
30 if a="Ohio" then goto 50
40 if a<>"Ohio" then goto 10
50 input "Correct! Type 'next' for the next question.";b
60 if b="next" then goto 70
70 home
80 input "What month is this?";c
90 if c="February" then goto 110
100 if c<>"February" then goto 70
110 print "Correct! Thus concludes this program."
120 end Corrected program:
10 HOME
20 PRINT "WHAT STATE DO YOU LIVE IN" : INPUT STATE$
30 IF STATE$ = "OHIO" THEN 50
40 GOTO 10
50 PRINT "CORRECT! TYPE NEXT TO CONTINUE" : INPUT B$
60 IF B$ = "NEXT" THEN PRINT "OK"
70 HOME : PRINT "WHAT MONTH IS IT TODAY" : INPUT MONTH$
80 IF MONTH$ = "FEB" THEN 90
85 GOTO 60
90 PRINT "CORRECT! THIS IS THE END."
100 END This has been tested on that simulator and works OK. Note: the syntax "THEN GOTO 100" can be shortened to "THEN 100"
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Posted by: luddite on 2009-02-25 11:56:09
On the original ][ and ][+ keyboard input was all upper case on a stock configuration. The IIe and IIC, however, have a working shift key.
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Posted by: Apostrophe on 2009-02-25 14:12:33
Hi,
Okay, l added the string variables, and it works perfectly! I guess I just made a few errors beforehand...
Just one more question, though...those two buttons labeled 'keyboard' and '80/40'...what do they do? I didn't press them because I don't want to screw anything up.
I believe that keyboard simply switches the layout to Dvorak and back again to Qwerty--is this true? And, I'd hazard a guess that the 80/40 key switches the resolution in GR mode to 80X80 and back again to 40X40.
How far off am I?
-Apostrophe
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Posted by: luddite on 2009-02-25 19:50:20
I believe that keyboard simply switches the layout to Dvorak and back again to Qwerty--is this true? And, I'd hazard a guess that the 80/40 key switches the resolution in GR mode to 80X80 and back again to 40X40.How far off am I? Not too far... you're right about the keyboard switch, but the 80/40 switch is for text not graphics. Play with them all you want, they won't hurt anything.
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Posted by: Dog Cow on 2009-02-26 10:38:01
The IIe and IIC, however, have a working shift key. I know that, I'm just old-school. 😛
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Posted by: Apostrophe on 2009-02-28 18:09:54
The more I use my Apple IIc, the better I get at programming it. But there's one thing that I still don't understand. I still haven't figured out what the 80/40 key does. I know how to use the Keyboard key and what it does, but not so with the 80/40 key. I press it, type a bit, and nothing else happens.
What exactly does that 80/40 key do?
-Apostrophe
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Posted by: luddite on 2009-02-28 18:22:43
What exactly does that 80/40 key do? According to wikipedia "an “80/40”-column switch for (specially-written) software to detect which text video mode to start up in"
Since the IIc is the only Apple II to have the 80/40 switch, I'd guess most programs wouldn't bother with it... especially since 80 and 40 column text modes can be accessed easily via software.
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Posted by: arfink on 2009-03-31 11:25:38
I do know AppleWorks does pay attention to that switch. You could conceivably use the switch for other things, as it just flags a certain address in memory. I doesn't actually do anything but that.
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