using the /c modifier (for not resetting pos if matching fails, see perlretut#Global matching) avoids an endless loop, but has strange effects, too:

This code 

use warnings;
$\="\n";
$str = 'ABC';
print "-"x10;
print pos($str);
pos($str) = 1;
while ($str=~/.\G/gc) {
  print $&;
}
print pos($str);
 
#__DATA__
# pos($str) = pos($str);     
while ($str=~/.\G/gc) {
  print $&;
}
print "-"x10;

[download]

prints: 

----------
Use of uninitialized value in print at /home/lanx/B/PL/PM/re_escG.pl l
+ine 5.
 
A
1
----------

[download]

but uncommenting line pos($str) = pos($str); prints 

----------
Use of uninitialized value in print at /home/lanx/B/PL/PM/re_escG.pl l
+ine 5.
 
A
1
A
----------

[download]

weird!

Cheers Rolf

In reply to Re: [bugs?] perldoc perlre, \G and pos() (and /c) by LanX
in thread [bugs?] perldoc perlre, \G and pos() by LanX

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.