Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask

Comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

possibly depending on an undocumented implementation detail of my version of Perl.

You most definitely are. The loop is suppose to take a list over which to iterate, but you're relying on the observable differences between that an the actual optimised implementation. You can see this by changing foreach (@arr) to what should be equivalent foreach ((),@arr).

Either iterate over the indexes

my @arr = qw/a b c/; for (my $i=0; $i<@arr; ++$i) { my $e = $arr[$i]; push @arr, 'd' if $e eq 'a'; push @arr, 'e' if $e eq 'b'; push @arr, 'f' if $e eq 'c'; print $e; } print "\n";

Or use a queue

my @arr = qw/a b c/; while (@arr) { my $e = shift(@arr); push @arr, 'd' if $e eq 'a'; push @arr, 'e' if $e eq 'b'; push @arr, 'f' if $e eq 'c'; print $e; } print "\n";

In reply to Re^3: Is it safe to append to the array you are iterating over by ikegami
in thread Is it safe to append to the array you are iterating over by DrWhy

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, 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, 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.
  • Log In?

    What's my password?
    Create A New User
    and God said, "Let Newton be!"...

    How do I use this? | Other CB clients
    Other Users?
    Others pondering the Monastery: (1)
    As of 2018-01-21 12:19 GMT
    Find Nodes?
      Voting Booth?
      How did you see in the new year?

      Results (228 votes). Check out past polls.