For testing "every third iteration," I do this sometimes:

my $n = 0;
foreach (@array) {
    next if I_dont_care_about($_);
    do_something_with ($_);
    print "." if !($n++ % 3);
}
print "\n";

[download]
If you aren't necessarily processing every item in the list, but only want to count the number of elements you process, then using a temporary variable as you were doing is a useful alternative to looping over the array indices. It also works when you're doing things like looping over hash keys, where you can't count on having a numeric index implicitly; or processing lines of a file with a while (<>) loop.

Update: KM, that is definitely true, and a more efficient and succinct way to count lines when you're interested in the total line count. The method I presented is still useful when you want to count the number of lines you processed, not the total line count so far.

Alan

In reply to Re: Of foreach loops and counting by ferrency
in thread Of foreach loops and counting by Cirollo

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.