GNU bug report logs - #13394
Misalignment for "seq -w"

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Message #19 received at 13394 <at> debbugs.gnu.org (full text, mbox):

From: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
To: 13394 <at> debbugs.gnu.org, P <at> draigBrady.com, hawkie <at> web.de
Subject: Re: bug#13394: Misalignment for "seq -w"
Date: Wed, 09 Jan 2013 13:14:37 +0100

On 01/09/2013 01:05 PM, Pádraig Brady wrote:
> On 01/09/2013 11:01 AM, Erik Auerswald wrote:
>> Hi,
>>
>> On 01/09/2013 11:34 AM, Bernhard Voelker wrote:
>>> On 01/09/2013 11:14 AM, Marcel Böhme wrote:
>>>>
>>>> There are the following problems with the -w parameter of the seq tool:
>>>> [...]
>>>
>>> Hmm, according to the TEXI manual, the FIRST number should also use
>>> a fixed point decimal representation when the -w option is used:
>>> [...]
>>> But that leaves the question open if there's a reason for this.
>>> I.e. if it's just documented behavior, a requirement of some
>>> standard or due to compatibility reasons.
>>
>> That seems to be just documented behavior, since seq is not
>> standardized by POSIX and other seq implementations ([1],[2],[3])
>> don't document this. On the contrary, a common example is 'seq -w 0
>> .05 .1'.
>>
>> This example works fine with GNU seq:
>>
>> $ seq -w 0 .05 .1
>> 0.00
>> 0.05
>> 0.10
>>
>> Even when counting to negative numbers:
>>
>> $ seq -w 0 -.05 -.1
>> 00.00
>> -0.05
>> -0.10
>>
>> Starting with a negative number with a fractional step size breaks
>> equal width for non-negative numbers:
>>
>> $ seq -w -1 .5 1
>> -1.0
>> -0.5
>> 0.0
>> 0.5
>> 1.0
>>
>> $ seq --version | head -n1
>> seq (GNU coreutils) 8.13
>
> Looks like a bug. I'll fix with:
>
> diff --git a/src/seq.c b/src/seq.c
> index e1b467c..3eb53f8 100644
> --- a/src/seq.c
> +++ b/src/seq.c
> @@ -332,6 +332,8 @@ get_default_format (operand first, operand step,
> operand last)
> last_width--; /* don't include space for '.' */
> if (last.precision == 0 && prec)
> last_width++; /* include space for '.' */
> + if (first.precision == 0 && prec)
> + first_width++; /* include space for '.' */
> size_t width = MAX (first_width, last_width);
> if (width <= INT_MAX)
> {

The patch looks plausible. ;-)

Thanks,
Erik

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