Re: [FWP] Is this fun? What's going on?

[Ronald J Kimball <rjk@linguist.dartmouth.edu>]

On Tue, Aug 10, 1999 at 01:59:56PM -0400, Bill Jones wrote:
> Given:
> 
> s{((\d+\.)(?:\d+)+)} {<A HREF="nav$2html">$1</A>}g;
> 
> Why does the first match '$1" get the whole match, and
> '$2' is getting the partial (which I feel is arriving
> from the first (\d+\.)  ?

Capturing parentheses count from the left:

m/((\d+\.)(?:\d+)+)/
  11111111111111111
   2222222


> However, this new match isn't really picking up the
> complete first match.  IE -
> 
> I have 1.2 and it matches 1.2 and 1. respectively;
> but when I have 1.2.3 - the .3 is lost...

Your regex only allows a single period.  You can't match all of '1.2.3',
because that contains two periods.


> Where 1.2.3.? = book.chapter.section.keyword.et al...
> 
> What I wanted was -
> 
> $1 = complete match, $2 = book and chapters, etc.

m/((\d+)(?:\.\d+)+)/;


> (or, maybe have $3 = chapters, and $4 = sections?)

You can't do that without knowing how many pieces you want ahead of time.
Try this instead:

if (m/(\d+(?:\.\d+)+)/) {
    @pieces = split /\./, $1;
}


> I even tried:
> 
> (?=\d+(?:\.\d+)+)  but then nothing shows up in $2...

No capturing parentheses at all.  Nothing will show up in $1 either.


Ronald


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