On Mon, Feb 10, 2025 at 09:50:01 +0100, Phi Debian wrote:
> On Sat, Feb 8, 2025 at 8:51 AM Robert Elz <k...@munnari.oz.au> wrote:
> > There are a gazillion different ways of getting rid of the octal
> > conversion "problem", one I prefer in cases where I know the value
> > is 2 digits, always, but might be 0n for 0<=n<=9, is $(( 1$x - 100 ))
> >
> gazillion++
> You say "I know the value is 2 digits" you forgot to say in base 10 but it
> was kinda implicit in the thread, then a more general one not limited to 2
> decimal digit accepting leading 0 you could simply do $((10#$i))
This issue comes up all the time.
Both of these solutions have limitations on what kind of input they'll
accept. Robert's only works on two-digit unsigned inputs. Phi's
works only on unsigned inputs of any length.
hobbit:~$ var=-023
hobbit:~$ echo "$((1$var - 100))"
-118
hobbit:~$ echo "$((10#$var))"
bash: 10#: invalid integer constant (error token is "10#")
The following line noise is the best *general* answer we've found
so far:
$((${num%%[!+-]*}10#${num#[-+]}))
See:
<https://mywiki.wooledge.org/ArithmeticExpression#Leading_Zeros_and_Base_Selection>
<https://lists.gnu.org/archive/html/bug-bash/2018-07/msg00033.html>
