SPUG: When is a caret just a caret? And what about dollar?

Charles DeRykus derykus at gmail.com
Sat Aug 22 05:26:38 PDT 2009


No, caret needs backwhacking to be a self-match:

perl -wle "use re 'debug'; /^^/"
    Compiling REx "^^"
    Final program:
      1: BOL (2)
      2: BOL (3)
      ....

perl -wle "use re 'debug'; /^\^/"
       Compiling REx "^\^"
       Final program:
       1: BOL (2)
       2: EXACT <^> (4)
        ....

-- 
Charles DeRykus

On Fri, Aug 21, 2009 at 11:47 PM, Michael R. Wolf <MichaelRWolf at att.net>wrote:

> I seem to remember that the meaning of caret in a regex is
> context-sensitive, and it can be an anchor, a complement, or just (with
> apologies to Sigmond) a caret.
>
> My memory is that .  Ergo, /^^[^^]^/ would match "beginning of line then
> caret then anything-but-a-caret then caret".  I can't seem to find support
> for this (long-held) belief.  Have I been wrong for this long?
>
> And while I'm at it, how 'bout dollar?  I thought it was an anchor iff it
> was the last character in the regex, else it introduced a scalar variable
> for interpolation.
>
> It seems that the documentation says that caret and dollar are *always*
> metacharacters.  Any ideas how I could have been mislead by a (seemingly)
> similar set of rules that I may have misinterpreted?  Has their meaning
> changed in previous versions of Perl (or the Perl regex engine)?
>
>
>
> --
> Michael R. Wolf
>    All mammals learn by playing!
>        MichaelRWolf at att.net
>
>
>
>
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