For speed, I'd suggest:

  sub test6 {
    my $n = $_[0] & $_[1];
    my $count = 0;
    ++$count, $n &= $n - 1 while $n;
    $count;
  }

[download]

For beauty I'd suggest hiding that behind a suitable function name - it costs an extra function call, but you can probably lose that in the way you call it when not benchmarking:

  sub countbits {
    my($n, $count) = ($_[0], 0);
    ++$count, $n &= $n - 1 while $n;
    return $count;
  }
  sub test7 {
    my($iDays, $iCmp) = @_;
    return countbits($iDays & $iCmp);
  }

[download]

You might even want to add some comments. :)

Benchmarks:

          Rate Test4 Test5 Test7 Test6
Test4 106192/s    --  -38%  -40%  -57%
Test5 172463/s   62%    --   -3%  -31%
Test7 176987/s   67%    3%    --  -29%
Test6 248686/s  134%   44%   41%    --

[download]

Hugo

In reply to Re: Loops loosing Performance by hv
in thread Loops loosing Performance by PerlingTheUK

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.