[bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[Joel J. Adamson]

URL:
  <http://savannah.gnu.org/bugs/?31893>

                 Summary: ice-9 format produces control characters and
non-printable characters for numeric output
                 Project: Guile
            Submitted by: trashbird1240
            Submitted on: Wed 15 Dec 2010 03:58:34 PM EST
                Category: None
                Severity: 3 - Normal
              Item Group: None
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any

    _______________________________________________________

Details:

Format produces non-printable output for certain expressions:

In an Emacs *shell* buffer:

scheme@(guile-user)> (format #t "~{~9,8,,,0g ~}~%" '(0.001 2.8 0.00))




    _______________________________________________________

File Attachments:


-------------------------------------------------------
Date: Wed 15 Dec 2010 03:58:34 PM EST  Name: ss_theory_scm.tar.gz  Size: 4kB 
 By: trashbird1240

<http://savannah.gnu.org/bugs/download.php?file_id=22211>

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?31893>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/

[bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[Andy Wingo]

Follow-up Comment #1, bug #31893 (project guile):

Very interesting! We can make the test case shorter:

> (format #f "~9,8,,,0g" 0.001)
$1 = "x00x00x00x00x00x00x00x00x00"


I think the x00 bytes are because of the recent make-string change
(3ef6650def28f7c29a2cc983086468d3195167d4). The control chars you were seeing
previously were just random bytes from memory (!), whatever was there before
make-string was called.

I'm on it!

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?31893>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/

[bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[Andy Wingo]

Update of bug #31893 (project guile):

                  Status:                    None => Invalid                
             Open/Closed:                    Open => Closed                 

    _______________________________________________________

Follow-up Comment #2:

Actually I think this problem is less exciting. Your format was:

~9,8,,,0g

So you are specifying a width of 9 chars, 8 mantissa digits, and an "overflow
character" of zero, which also has the effect of making the width a hard
limit. Also note that your overflow char is (integer->char 0), not #  -- the
nul byte, indeed a control character.

In this case the width of the whole thing will always be more than 9
characters, so we always splat in the overflow char, which is #nul -- leading
to the result given in my first comment.

In the future for debugging these things, don't print to the terminal --
print to a string instead. That will be clearer.

Cheers,

Andy

    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?31893>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/

Re: [bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[Joel J. Adamson]

[-- Attachment #1: Type: text/plain, Size: 751 bytes --]

Andy Wingo <INVALID.NOREPLY@gnu.org> writes:

> Actually I think this problem is less exciting.

This is exactly what I was hoping for!

> Your format was:
>
> ~9,8,,,0g
>
> So you are specifying a width of 9 chars, 8 mantissa digits, and an
> "overflow character" of zero, which also has the effect of making the
> width a hard limit. Also note that your overflow char is
> (integer->char 0), not # -- the nul byte, indeed a control character.

This makes sense.  Using just "~f " fixed some of the output, but not
all.  I will work more with the format strings.

Thanks,

Joel

-- 
Joel J. Adamson	-- http://www.unc.edu/~adamsonj
University of North Carolina at Chapel Hill
CB #3280, Coker Hall
Chapel Hill, NC 27599-3280

[-- Attachment #2: Type: application/pgp-signature, Size: 197 bytes --]

Re: [bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[Andy Wingo]

On Mon 20 Dec 2010 03:55, adamsonj@email.unc.edu (Joel J. Adamson) writes:

> Andy Wingo <INVALID.NOREPLY@gnu.org> writes:
>
>> ~9,8,,,0g
>
> Using just "~f " fixed some of the output, but not
> all.  I will work more with the format strings.

Note that '0 instead of 0 will pad with #\0 instead of #\nul.

Happy hacking,

Andy
-- 
http://wingolog.org/

Re: [bug #31893] ice-9 format produces control characters and non-printable characters for numeric output

[Joel J. Adamson]

[-- Attachment #1: Type: text/plain, Size: 621 bytes --]

Andy Wingo <wingo@pobox.com> writes:

> On Mon 20 Dec 2010 03:55, adamsonj@email.unc.edu (Joel J. Adamson) writes:
>
>> Andy Wingo <INVALID.NOREPLY@gnu.org> writes:
>>
>>> ~9,8,,,0g
>>
>> Using just "~f " fixed some of the output, but not
>> all.  I will work more with the format strings.
>
> Note that '0 instead of 0 will pad with #\0 instead of #\nul.

Thanks: I think what I really need is some gauze to pad the empty spaces
inside my brain.

Joel

-- 
Joel J. Adamson	-- http://www.unc.edu/~adamsonj
University of North Carolina at Chapel Hill
CB #3280, Coker Hall
Chapel Hill, NC 27599-3280

[-- Attachment #2: Type: application/pgp-signature, Size: 197 bytes --]