Re: Confusion about code sample in perlfaq4

[BrowserUk]

Don't they want to get a list "e.g. ( 1, 0, 0, 1, 1, 0 ... )" as stated in the beginning of that section,

Why not just try it out?

$vec = pack 'V', int( 2**32* rand() );;

print $bits;;
011000001111110110010000101101

@ints = (); 
{ 
    use integer; 
    push @ints, 0 if $bits =~ s/^(\d)// && $1;
    push @ints, pos $bits while $bits =~ /1/g;
};;

print @ints;;
1 2 8 9 10 11 12 13 15 16 19 24 26 27 29

The are producing a list of the positions of the bits that are set.

I do agree that the section title and description and the sub name are woefully bad.

I'm also less than impressed with the claims for efficiency:

C:\test>perl -MMath::Random::MT=rand -minteger -MBenchmark=cmpthese
$vec = pack 'V*', map int( 2**32* rand() ), 1 ..10;;
cmpthese -1, {
 a=>q[ my @ints; my $bits = unpack 'b*', $vec; use integer; push @ints
+, 0 if $bits =~ s/^(\d)// && $1;push @ints, pos $bits while($bits =~ 
+/1/g); ],
 b=>q[ my @ints = grep{ vec( $vec, $_, 1 ) } 0 .. length( $vec ) -1; ]
+,
};;
^Z
      Rate    a    b
a  22306/s   -- -79%
b 108646/s 387%   --