Divide By Zero (RT Error 11) Print Error

[Phil Porter]

We are using an 850 MHz all-in-one CPU card running in a micro-
box for a process control application. During troubleshooting it
was noticed that adding a print statement would cause a very
repeatable Error 11 (Divide by zero) at runtime. Remove the
print statement and the error goes away.

TurboPascal had a bug in its CRT module which resulted in the
same divide by zero error message. There are several patches
that can be downloaded from the Internet to fix this bug.

My question is ... does PowerBASIC have a patch to fix this bug
in the PowerBASIC/DOS V3.5 library?

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[Mel Bishop]

To the best of my knowledge, PB is the most bug free compiler on
the market. There are no known issues with the PRINT (I assume
to screen) statement. Perhaps if you posted a code snippet, we
could take a look at it.

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[Lance Edmonds]

There have been ZERO bugs reported along these lines, whatsoever. That said, if your PB.EXE is dated 19/12/97 then you are using the very latest build (build 19).

However, from the description I would fully expect the problem to be in the program itself and that program is not using $ERROR ALL ON... hence the real error is quite probably occurring somewhere prior to the PRINT statement.

Importantly, it is likely that the real cause of the crash might not be a division-by-zero error either... it could just be the symptom of a memory corruption that occurs when code writes beyond the boundary of an array (and overwriting memory being used for other variables, pointers, program code, etc).

Also, memory corruption can be caused by all kinds of things, including buggy memory managers, poorly written inline-assembler code, misuse of pointers, bugs in 3rd-party apps such as TSR's, etc.

Basically, compiled code [that does not have all 4 optional error tests active] won't check for errors after every BASIC statement, etc. However, I/O operations (such as PRINT, OPEN, etc) will always check the state of ERR and react accordingly, regardless of the $ERROR metastatement.

Therefore, when an "unexpected" crash is seen at a PRINT or other I/O statement, you'll know what to do!



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Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Jerry Mason]

This is sure to get me flamed, but here goes...

The fastest way to get rid of that error, Phil, is to put a
$SEGMENT statement in your code.

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[Bob Zale]

Originally posted by Jerry Mason:
This is sure to get me flamed, but here goes...

The fastest way to get rid of that error, Phil, is to put a
$SEGMENT statement in your code.

This suggestion is absolutely incorrect. Following this advice is guaranteed to do nothing but waste your time.

The information supplied by Lance Edmonds is 100.0% accurate and guarantees success.

Bob Zale
PowerBASIC Inc.


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[Phil Porter]

Gentlemen,

All help is appreciated. I'm sitting at 7,000+ lines of
PowerBASIC code for our process application and management is
impressed with the quality of the application so far. It will
be difficult to offend me because I just picked up BASIC, and
PowerBASIC in particular, to code this application because we
wanted an MSDOS-supported compiler environment. Hence, I'm
still learning all the nuances about PowerBASIC. We resolved
the problem by removing the troubleshooting print statement but
Lance's thoughts are undoubtedly correct in that the problem
does mimic a memory overwrite error. We'll use the
recommendations from this forum going forward. Thanks again.

Phil ...

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[Bob Zale]

Phil--

Removing the PRINT is not going to help over the longer term. It will simply shift the exception report to another statement later. The important thing is to find the line of code which is actually causing a problem, since the exception may have occured long before the PRINT.

As Lance mentioned, just add an $ERROR ALL ON and run it again. You likely find the problem in seconds.

Regards,

Bob Zale
PowerBASIC Inc.


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[Phil Porter]

Bob,

I will do that today. We are coding the control room touch
screen interface portion of the application using Delphi and
Windows so I'm timesharing between the two languages/OSs.
Your support is appreciated and was one of the reasons that we
opted to license several copies of PB/DOS V3.5.

Thanks again,

Phil ...

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