[kw-pm] $1 matching question

[rprice at freeshell.org]

Did it fail to assign to the value when it did not get a match rather than
assigning Undef to it?

Rick


On Wed, 21 Jul 2004, Daniel R. Allen wrote:

> I've got a regex question that I'm probably just being stupid about:
>
> bash% echo -e "9 \n \n 2" | perl -ne'/(\d+)/; print "$1 ";'
>
> has the following result:
>
> 9 9 2
>
> Shouldn't it be '9  2' ?  And the result is the same with:
>
> bash% echo -e "9 \n \n 2" | perl -ne'$z = ""; /(\d+)/; $z = $1; print "$z
> " if $z;'
>
> Which means $1 is actively being assigned to, when there isn't a match!
>
> deparse tells me:
>
> bash% perl -MO=Deparse -ne'/(\d+)/; print "$1 ";'
> LINE: while (defined($_ = <ARGV>)) {
>     /(\d+)/;
>     print "$1 ";
> }
>
> ...which looks just like I'd expect.  Maybe I just took a stupid pill this
> morning.
>
>
> -Daniel
>
> --
> "Use a different web browser. There are a number of significant vulnerabilit-
> ies in technologies relating to the [Microsoft] IE domain/zone security model,
> the DHTML object model, MIME type determination, and ActiveX."  - US CERT (US
> Computer Emergency Readiness Team) - http://www.kb.cert.org/vuls/id/713878
>
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