Re: Strange behavior with "for i in .."

[Peter Stephenson <Peter.Stephenson@csr.com>]

On Fri, 23 Sep 2011 13:29:49 +0300
Volodya Khomchak <kolombo.inc@gmail.com> wrote:
> I faced with strange behavior with "for i in ..".
> So the problem is next:
>    # for i in /etc/profile.d/*.sh;do echo $i;done
>    # zsh: bad math expression: operand expected at `/etc/profi...'
> But if I change "i" to "file" it would work:
>    # for file in /etc/profile.d/*.sh;do echo $file;done
>    # /etc/profile.d/1.sh
>    # /etc/profile.d/2.sh
> 
> zsh --version
> zsh 4.3.10 (x86_64)
> 
> So what is going on here ?

Probably the first time i is referred to in the shell was in something like

  for (( i = 0; i < stuff; i++ )); ...

or, in fact, any arithmetic involving "i".  This has caused "i" to be
implicitly typed as an integer.  This only happens if i doesn't exist at
that point.

There are various things you can do;

  typeset i

before you use i the first time will ensure it's a scalar (i.e. string)
value even if you use it in arithmetic subsequently.

Or,

  typeset +i i

before you use it for any other purpose than arithmetic.

Or, if the original use was in initialisation code and you don't want i
to be exposed by it, simply

  unset i

after that would be good enough.

Or, of course, you can keep i for integers and use another variable for
strings, which is in effect what you tried.

-- 
Peter Stephenson <pws@csr.com>            Software Engineer
Tel: +44 (0)1223 692070                   Cambridge Silicon Radio Limited
Churchill House, Cambridge Business Park, Cowley Road, Cambridge, CB4 0WZ, UK


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