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Forum Index : Microcontroller and PC projects : MMB4W: Function error, possible bug?

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LeoNicolas

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Joined: 07/10/2020
Location: Canada
Posts: 504

Posted: 06:11am 24 Dec 2023

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The following code ends with the error: Error in line 15: FUNC is not declared.

option explicit

main()

sub main()
local i%

for i%=0 to 4
func1()
next
end sub

function func1() as integer
func1=10
end function

If I change the code as follows it works fine:

option explicit

main()

sub main()
local i%, ret

for i%=0 to 4
ret=func1()
next
end sub

function func1() as integer
func1=10
end function

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 07:13am 24 Dec 2023

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It's a function so it needs to do something with the return.
Because you had no var to accept the return, it went looking for a SUB

Jim

VK7JH
MMedit

Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 3292

Posted: 08:14am 24 Dec 2023

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It is tempting to think that something not working as you expected as a bug in the compiler/interpreter - but 99.999% of the time it is not.

We all fall into this trap from time to time.

Geoff

Geoff Graham - http://geoffg.net

Mixtel90

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Joined: 05/10/2019
Location: United Kingdom
Posts: 7937

Posted: 08:26am 24 Dec 2023

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Oh yes....
Tell me about it.... :(
I'm forever being outsmarted by a bit of silicon!

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

LeoNicolas

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Joined: 07/10/2020
Location: Canada
Posts: 504

Posted: 03:22pm 24 Dec 2023

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Sorry for my false positive bug post.

This is interesting. I can imagine why It happens. Probably the variable pointer is used directly for the func routine to store the return value, instead of having another memory allocation just for holding the value while the function is executed. Of course I can be completely wrong.

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 10315

Posted: 03:33pm 24 Dec 2023

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Quote Of course I can be completely wrong.

Yes. The first thing in a line is always an in-built command or a user SUBROUTINE. A function must always be assigned to something, typically using the in-built command LET which is the default if there is an =

i.e. ret=func1() is actually interpreted ad LET ret=func1()

Func1() at the start of a line fails the interpreter lookup for either an in-built command or a use subroutine hence the error

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