Re: Number with sign is read as octal despite a leading 10#

[Ilkka Virta]

For what it's worth, ksh and zsh seem to interpret  10#-0159
as negative one-hundred and fifty-nine:

$ ksh -c 'for a do a="10#$a"; printf "%s " $((a + 1)); done; echo' \
  sh +159 +0159 -159 -0159
160 160 -158 -158
$ zsh -c 'for a do a="10#$a"; printf "%s " $((a + 1)); done; echo' \
  sh +159 +0159 -159 -0159
160 160 -158 -158

$ ksh --version
  version         sh (AT&T Research) 93u+ 2012-08-01
$ zsh --version
zsh 5.3.1 (x86_64-debian-linux-gnu)


On 10.7. 13:44, Ilkka Virta wrote:
> I think the problematic case here is when the number comes as input from 
> some program, which might or might not print a leading sign or leading 
> zeroes, but when we know that the number is, in any case, decimal.
>
> E.g. 'date' prints leading zeroes, which is easy enough to handle:
>
> hour=$(date +%H)
>
> hour=${hour#0}         # remove one leading zero, or
> hour="10#$hour"        # make it base-10
>
> The latter works even with more than one leading zero, but neither works 
> with a sign. So, handling numbers like '-00159' gets a bit annoying:
>
> $ num='-00159'
> $ num="${num:0:1}10#${num:1}"; echo $(( num + 1 ))
> -158
>
> And that's without checking that the sign was there in the first place.
>
>
> Something like that will probably not be too common, but an easier way 
> to force any number to be interpreted in base-10 (regardless of leading 
> zeroes) could be useful. If there is a way, I'd be happy to hear.
>
>
> On 10.7. 04:37, Clint Hepner wrote:
> > The + is a unary operator, not part of the literal. Write 
> > $((+10#0034)) instead.
> >
> > --
> > Clint
> > On Jul 9, 2018, 9:24 PM -0400, Isaac Marcos 
> > <isaacmarcos100010@gmail.com>, wrote:
> > > Configuration Information [Automatically generated, do not change]:
> > > Machine: x86_64
> > > OS: linux-gnu
> > > Compiler: gcc
> > > Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64'
> > > -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu'
> > > -DCONF_VENDOR
> > > uname output: Linux IO 4.9.0-6-amd64 #1 SMP Debian 4.9.88-1+deb9u1
> > > (2018-05-07) x86_64 GNU/Linux
> > > Machine Type: x86_64-pc-linux-gnu
> > >
> > > Bash Version: 4.4
> > > Patch Level: 12
> > > Release Status: release
> > >
> > > Description:
> > > A value inside an arithmetic expansion is processed as octal despite 
> > > using
> > > a 10# preffix.
> > >
> > > Repeat-By:
> > > $ echo $((10#+0034))
> > > 28
> > >
> > > Fix:
> > > Extract optional sign before parsing the number, re-attach after.
> > >
> > > --
> > > Cases are always threesome:
> > > Best case, Worst case, and Just in case


--
Ilkka Virta / itvirta@iki.fi