Hi Sam,
Perl's regex engine finds the left-most match

I would have phrased it like this: like most engines Perl's looks by default for the longest leftmost match. 

% stephan@labaule (/home/stephan) %
% echo "okay stephan do test it!" |                                   
+        
> perl -lne 'm!(steph.?)!; print "seen: [$1]\n"'
seen: [stepha]

[download]

Actually POSIX mandates longest possible for alternations as they all start at the same place. The owl book calls that POSIX NFA. 

% stephan@labaule (/home/stephan) %
% echo "okay stephan do test it!" | 
> perl -lne 'm!(steph|steph.?)!; print "seen: [$1]\n"'
seen: [steph]

[download]

so yes, perl's is not POSIX NFA (for various efficiency reasons)

Actually not many engines follow POSIX on this, mostly (ugly -- because too ancient) system libraries (on Un*x), ksh's does too, even the Hackerlab library does (on second thought seems normal as it was supposed to be a drop-in replacement for the C lib on Un*x -- and POSIX). Tcl's is hybrid so I am not sure. And every engine after Perl5 birth has essentially copied Perl's.

regards --stephan
by the way ksh notation is interesting (zsh can masquerade as ksh for this if you don't have a ksh to try)

In reply to Re^2: question about the star(*) quantifier by sgt
in thread question about the star(*) quantifier by snowsky

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.