XML CO538 Anonymous Questions and Answers Keyword Index

This page provides a keyword index to questions and answers. Clicking on a keyword will take you to a page containing all questions and answers for that keyword, grouped by year.

To submit a question, use the anonymous questions page. You may find the keyword index and/or top-level index useful for locating past questions and answers.

Keyword reference for range-error

Question 12 (2007):

Submission reference: IN1309

I am working on q3.occ and trying to get occam to throw some runtime errors. I am attempting to create a array out of bounds error. I manage to get a runtime error but the output then calls it a CSUB0 error.

Is this what I want? What is it? Cheers

Answer 12:

Yes, this is the error you get when attempting to access a non-existent array element. CSUB0 is the Transputer instruction that implements a particular range-check, and happens to be used when generating code that checks for array-bounds errors. Unfortunately that error message is not particularly user-friendly, something we plan to fix at some point in the future..

Keywords: range-error , q3

Question 103 (2003):

I have problems with this range error:

    KROC: Range error / STOP executed (signal 4) 
    KROC: Fatal error code 1, core dumped
    Abort (core dumped)    

I have looked at the past Anonymous question pages. But none seem to be the problem. I run my program and it seems to run fine. Occasionally it crashes with the range error above. This normally happens about 10 minutes into running it, however it can sometimes occur just after 10 seconds. I'm not quite sure what else could be the problem as I think that after 10 mins of running the process that it would have excuted all of the code at least once.

Here's the list I found that I have checked against:

• accessing an illegal array index (e.g. negative or too large)
• executing an IF statement all of whose conditions are FALSE
• executing an ALT statement all of whose guards are pre-conditioned and all of which pre-conditions are FALSE
• casting from one numeric type to another, but the number being cast is not in the range of the target type
• receiving a variant of a CASE protocol in a CASE input statement that is not programmed to receive that variant. We are not obliged to cater for all variants of the protocol - but, if we don't, we must know that the omitted variants will not be sent
• executing an explicit STOP

any suggestions of what i could do to elimate this very annoying bug ???

Answer 103:

The biggest clue as to what is going wrong is the fact the timing of the crash varies. At a guess, the error is the result of time manipulation using `+' instead of `PLUS', or other arithmetic involving `time' that does not use non-overflowing operators (TIMES, PLUS and MINUS).

As has been said in other posts, if you want more information on the error, you'll need to run with (run-time) debugging enabled. This is only supported on KRoC/Linux at the moment.

Keywords: range-error , stop

Referrers: Question 31 (2012) , Question 9 (2004) , Question 43 (2004)

Question 47 (2003):

I have written my `q6' using a pipeline of cells with the cells written in a similar style to the `display' PROC (with IF statements to decide whether to send the incoming values on).

It compiles with no problems, but when I run it I get:

KROC: Range error / STOP executed (signal 4)
KROC: Fatal error code 1, core dumped
Abort (core dumped)

What is the likely reason for this ? I've checked through my code and it seems to be fine.

Answer 47:

Please refer to Question 30 (2003).

Keywords: q6 , range-error

Question 30 (2003):

my program keeps aborting when i run it, it shows this ...

    KROC: Range error / STOP executed (signal 11)
    KROC: Fatal error code 1, core dumped
    Abort (core dumped)

what is wrong here?

Answer 30:

This is the result of a run-time error in your occam program. These errors are caused by one of the following:

• executing a STOP
• arithmetic overflow on standard operations
• range error caused by array index out-of-bounds
• range error caused by a replicator's count being less than zero

However, the error doesn't tell you where or exactly what the error is. Post-mortem debugging is available in KRoC, but only for the Linux version at the moment -- you can use `gonzo' for this. Compiling with the `-d' flag will turn on debugging such that when the program crashes, it'll display a more useful error message (including the file-name and line-number where the error occurred).

See also the answer to Question 70 (2000).

Keywords: range-error , stop

Referrers: Question 31 (2012) , Question 47 (2003) , Question 72 (2003) , Question 86 (2003)

Question 11 (2002):

I get the following error when running my q4 on raptor, I have got up to part three, please could you give me some idea what this error means and what caused it.

  KROC: Range error / STOP executed (signal 4)
  KROC: Fatal error code 1, core dumped
  Abort (core dumped)

Answer 11:

Please see the answer to Question 70 (2000).

Keywords: range-error , stop

Question 70 (2000):

Once the first draft of my q7 program is compiled and run, it produces this error:

    Philosopher 1 is thinking
    KROC: Range error / STOP executed (signal 4)
    KROC: Fatal error code 1, core dumped
    Abort (core dumped)

I don't know what this means, so I would be grateful if you could point me in the right direction ...

Answer 70:

It means your program crashed. There are several possible causes of this run-time error:

• accessing an illegal array index (e.g. negative or too large);
• executing an IF statement all of whose conditions are FALSE;
• executing an ALT statement all of whose guards are pre-conditioned and all of which pre-conditions are FALSE;
• casting from one numeric type to another, but the number being cast is not in the range of the target type;
• receiving a variant of a CASE protocol in a CASE input statement that is not programmed to receive that variant. We are not obliged to cater for all variants of the protocol - but, if we don't, we must know that the omitted variants will not be sent;
• executing a STOP.

I'm afraid the message you report is all you get from the KRoC/Solaris system. If you compile this with KRoC/Linux using the command:

    kroc -d myfile.occ -lcourse

it will tell you the file name and line number of the offending line. [Note: the "-lcourse" flag above is just to link in the course library - something which is automatic with the Solaris version of the kroc command. The active ingredient of the above command is the "-d" flag.]

Keywords: q7 , range-error , stop

Referrers: Question 31 (2012) , Question 6 (2011) , Question 53 (2006) , Question 43 (2004) , Question 30 (2003) , Question 86 (2003) , Question 11 (2002)

Question 37 (2000):

I'm in the process of doing q4 and I've implemented everything except pairs. It all compiles but, when I run it, it immediately gives me an error:

  Range error / STOP executed (signal 4)
  Fatal error code 1, core dumped
  Abort (core dumped)

First thoughts were that I had used STOP wrong. However, I took it out and still got the same error. I can't work out where I could be going out of range, so I just wondered if you could explain the error message to me so I could work out what part of my code it is refering to.

Answer 37:

The run-time error messages are a bit terse, I'm afraid. The above error message can be caused by at least 4 things:

• execute a STOP;
• try to access an array element that's outside the range of its indices;
• try to cast too large an INT into a BYTE (or a negative etc.);
• all conditions in an IF construct turn out to be FALSE (see slide 4-44 and/or section 4.4 of "An Occam2 Checklist").

It's probably the last one that's your problem ...

Keywords: q4 , range-error , stop