Re: Feature request

[Oğuz]

9 Kasım 2020 Pazartesi tarihinde Dale R. Worley <worley@alum.mit.edu> yazdı:

> <vq@larryv.me> writes:
> >> On Nov 8, 2020, at 6:49 PM, Budi <budikusasi@gmail.com> wrote:
> >>
> >> Need feature on while's readily flag
> >>
> >> $ i=;while ((i<5)) ;do let i++ ;echo $i ;done ;echo $?
> >> 1
> >> 2
> >> 3
> >> 4
> >> 5
> >> 0
> >>
> >> $ i=7;while ((i<5)) ;do let i++ ;echo $i ;done ;echo $?
> >> 0
> >>
> >> we need feature on while's ability to supply flag when it's up to the
> >> end of loop block
> >
> > It's not clear what you're asking for. Do you want while to exit
> > nonzero when it doesn't perform any loops?
>
> I suspect what Budi wants is more explicit control of the exit value of
> the while block.  Of course, as long as the block is executed at least
> once, it is straightforward to control the exit value.  Compare these
> two examples:
>
> $ i=0;while ((i<5)) ;do let i++ ;echo $i; true ;done ;echo $?
>
> $ i=0;while ((i<5)) ;do let i++ ;echo $i; false ;done ;echo $?
>
> What cannot be controlled is the exit value if the block is not executed
> i.e. if the initial evaluation of the condition is false.  In that case,
> the exit value is always zero.
>
>
You're not saying this warrants a change to the while loop's behavior
though, right? There is nothing wrong with using an extra variable to
determine whether the loop body was ever reached.

    i=7
    j=0
    while ((i<5)); do
      let i++
      echo $i
      j=1
    done
    echo $j


> Dale
>
>

-- 
Oğuz