in reply to Capturing with look-ahead

Capture two chars inside the lookahead and throw in another dot afterwards to advance one character in the string: 

    $_ = 'blah';
    my @matches = /(?=(..))./g;
    print "@matches\n";

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Re: Re: Capturing with look-ahead
by japhy (Canon) on Mar 04, 2002 at 21:02 UTC
    The extra . isn't necessary, although I have a feeling it makes the regex more efficient.

    _____________________________________________________
    Jeff[japhy]Pinyan: Perl, regex, and perl hacker, who'd like a (from-home) job
    s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

[reply]
      Why is that? (?=) is zero-width, why does it look further one char next time?
[reply]
        I direct your attention to perlre, the section named Repeated patterns matching zero-length substring. This complicated section can be summarized by this extract: "the following match after a zero-length match is prohibited to have a length of zero."

        _____________________________________________________
        Jeff[japhy]Pinyan: Perl, regex, and perl hacker, who'd like a (from-home) job
        s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

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