Issue with string slices

Issue with string slices

[joão marcos pereira bezerra]

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Zsh is not printing the character "-"

Example 1:
arg="--help"
echo ${arg[1]}
echo ${arg[2]}
echo ${arg[3]}

Expected:
-
-
h

Got:
(new line empty)
(new line empty)
h


Example 2:
arg="--help"
echo ${arg:0:1}
echo ${arg:0:2}
echo ${arg:1:1}
echo ${arg:1:2}

Expected:
-
-
-
h

Got:
(new line empty)
--
(new line empty)
-h

Re: Issue with string slices

[Peter Stephenson]

On Mon, 2019-06-17 at 08:36 +0000, joão marcos pereira bezerra wrote:
> Zsh is not printing the character "-"

With echo, you mean --- I don't think this has got anything to do
with string slices.

Correct, this is documented as very long-standing behaviour.

       Note that for standards compliance a double dash does not termi-
       nate option processing; instead, it is printed  directly.   How-
       ever,  a  single  dash  does terminate option processing, so the
       first dash, possibly following  options,  is  not  printed,  but
       everything  following  it is printed as an argument.  The single
       dash behaviour is different from other shells.  For a more  por-
       table  way of printing text, see printf, and for a more control-
       lable way of printing text within zsh, see print.

pws

Re: Issue with string slices

[Roman Perepelitsa]

To print $something as is, use one of these forms:

  echo -nE - "$something"
  print -nr -- "$something"
  printf '%s' "$something"

The first two are ZSH specific, the last is portable. ZSH also allows
you to omit quotes here unless SH_WORD_SPLIT option is set.

Roman.

Re: Issue with string slices

[joão marcos pereira bezerra]

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Thanks guys, i was unsure if i should report this issue

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________________________________
From: Roman Perepelitsa <roman.perepelitsa@gmail.com>
Sent: Monday, June 17, 2019 6:05:32 AM
To: Peter Stephenson
Cc: Zsh hackers list; joão marcos pereira bezerra
Subject: Re: Issue with string slices

To print $something as is, use one of these forms:

  echo -nE - "$something"
  print -nr -- "$something"
  printf '%s' "$something"

The first two are ZSH specific, the last is portable. ZSH also allows
you to omit quotes here unless SH_WORD_SPLIT option is set.

Roman.

Re: Issue with string slices

[Stephane Chazelas]

2019-06-17 11:05:32 +0200, Roman Perepelitsa:
> To print $something as is, use one of these forms:
> 
>   echo -nE - "$something"
>   print -nr -- "$something"
>   printf '%s' "$something"
> 
> The first two are ZSH specific, the last is portable. ZSH also allows
> you to omit quotes here unless SH_WORD_SPLIT option is set.
[...]

The second one comes from ksh, it's not zsh-specific and
predates POSIX, let alone POSIX's printf, but nowadays is not as
portable as printf.

If you want to target zsh and ksh only, "print" may be more
desirable as there are still some pdksh derivatives where printf
is not built-in.

"unless SH_WORD_SPLIT *or GLOB_SUBST* is set"

-- 
Stephane