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BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 03:39pm 21 May 2013

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Hi all,

is there a limit toi the size of LOCAL variables in functions?

I'm getting an error: stack overflow. Expression is too complex.

The code:

Function fkey(funkey)
Local F$,I$
F$=Chr$(145)+Chr$(146)+Chr$(147)+Chr$(148)+Chr$(149)+Chr$(15 0)+Chr$(151)
F$=F$+Chr$(152)+Chr$(153)+Chr$(154)+Chr$(155)+Chr$(156)

key: I$=Inkey$:If I$="" GoTo key
funkey = Instr(1,F$,I$)
Return

What am I doing wrong?

Regards,

Bob Devries
Dalby, QLD, Australia

BobD

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Joined: 07/12/2011
Location: Australia
Posts: 935

Posted: 03:49pm 21 May 2013

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Typo?
Chr$(15 0)extra space

should that be Chr$(150) ?

Bob

BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 03:53pm 21 May 2013

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Hi Bob,

I checked that, but it seems to be an artifact of cutting and pasting into the forum.
There's no space in my code.

Regards,

Bob Devries
Dalby, QLD, Australia

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2914

Posted: 03:53pm 21 May 2013

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BobD said Typo?
Chr$(15 0)extra space

should that be Chr$(150) ?

Bob

I would expect that that problem would be the infamous `The Bad Shed' Add extra spaces to long lines (that arent broken by a space)

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 04:08pm 21 May 2013

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Hi All,

even if I remove the line that declares the LOCAL variables, I then get the same error on the line:

key: I$=inkey$:if I$="" then goto key

Have I unearthed a (dare I say it?) bug? Or am I doing something basically (pun intended) wrong?

Regards,

Bob Devries
Dalby, QLD, Australia

paceman
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Joined: 07/10/2011
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Posts: 1329

Posted: 05:08pm 21 May 2013

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Bob, I think I had this problem some time ago - try putting the label on a separate line,

key:
I$=inkey$:if I$="" goto key

Greg

BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 05:10pm 21 May 2013

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Ah, now that you mention it....

I'll give that a try.

Regards,

Bob Devries
Dalby, QLD, Australia

BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 05:17pm 21 May 2013

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Hi Greg & all,

Yep, that works now.
Strange thing is... if I put the same line as inline in the main body of the programme, no error is generated. Go figure.

Regards,

Bob Devries
Dalby, QLD, Australia

Geoffg

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Joined: 06/06/2011
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Posts: 3194

Posted: 05:28pm 21 May 2013

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Bob,

This is the first time that I have seen someone hit the "stack overflow" error. It is not caused by a local variable being too big - local variables have exactly the same rules as normal variables.

What happens is that the interpreter evaluates an expression by recursively calling itself and while doing that it saves temporary values onto the stack. The stack overflow error means that the expression is so complex that the interpreter has used up all the RAM reserved for the stack.

The problem here is that the expressions in the sample program are not nearly complex enough to cause this error. Also the loop at the label "key:" could not be causing a stack overflow because there is no complex expression there either.

I tried running the program but it does not run and it does not make any sense. You declare a function but there is no END FUNCTION statement, instead you use RETURN when there is no GOSUB to return to. I suspect that it is this mangled code that is somehow tripping up the interpreter which then runs off the rails causing the stack overflow error.

Geoff

Geoff Graham - http://geoffg.net

paceman
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Posted: 06:14pm 21 May 2013

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Geoffg said Bob,...... You declare a function but there is no END FUNCTION statement, instead you use RETURN when there is no GOSUB to return to. I suspect that it is this mangled code that is somehow tripping up the interpreter which then runs off the rails causing the stack overflow error.
Geoff

That's probably what I was doing too Geoff. At the time I remember I'd mixed up various combinations of "GOSUB", "FUNCTION", "END FUNCTION", "RETURN" and labels (no ":" on them) a couple of times before I fnally got the code working.
Greg

BobDevries

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Joined: 08/06/2011
Location: Australia
Posts: 266

Posted: 06:24pm 21 May 2013

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The final code which works is here:

Function fkey()
Local F$, I$
F$=Chr$(145)+Chr$(146)+Chr$(147)+Chr$(148)+Chr$(149)+Chr$(15 0)+Chr$(151)
F$=F$+Chr$(152)+Chr$(153)+Chr$(154)+Chr$(155)+Chr$(156)
F$=F$+"Q"+"q"

key:
I$=Inkey$:If I$="" Then GoTo key
fkey=Instr(1,F$,I$)
End Function

@Geoff:
You're probably right about what really caused the error. I had mixed up the function/end function with Gosub/Return.

I'd say the interpreter got confused; I know I was :P

Regards,

Bob Devries
Dalby, QLD, Australia

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