my $stime = time;

for (1..1_000_000) {
   my $i = rand(4294967295);
   while ($i) {
      $count++ if $i>>=2;
   }
}

my $etime = time;
print($etime-$stime, " seconds to count the $count 1s in 32_000_000 bi
+ts\n");
[download]

That isn't counting 1s. It kind of assigns a score from 0 to 15 based on how big the number is, with most numbers scoring 15, and it is equivalent to

   $count +=
      ($i > 2**2) +
      ($i > 2**4) +
      ($i > 2**6) +
      ...
      ($i > 2**26) +
      ($i > 2**28) +
      ($i > 2**30);
[download]

which on average gives 14 2/3. (3/4 of the numbers get 15, 3/4 of the remaining numbers get 14, 3/4 of the remaining numbers get 13, etc.)

To count 1s (one of many ways):

do {
   ++$count if $i & 1;
} while $i >>= 1;
[download]

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.