#!/usr/bin/perl
#
# $Id: for-loops 2592 2003-12-21 00:33:01Z jmates $
#
# The author disclaims all copyrights and releases this document into
# the public domain.
#
# for() loop speed comparisons.  May want to add meat to the loops.

use Benchmark qw(cmpthese);

@data = (a .. z, A .. Z);

# test the routines here
#&tag;

cmpthese(
  100000,
  {
    'c'       => \&forc,
    'perl'    => \&forperl,
    'perlish' => \&forperlish,
    'while'   => \&forwhile,
    'perlvar' => \&forperlvar,
  }
);

sub forc {
  for ($i = 0; $i < $#data; $i++) {
    ;
  }
}

sub forperl {
  for (@data) {
    ;
  }
}

sub forperlish {
  for (0 .. $#data) {
    ;
  }
}

sub forperlvar {
  for my $i (0 .. $#data) {
    ;
  }
}

# this is fast on threaded (5.005?) perls, slow otherwise
sub forwhile {
  local $_ = 0;
  while ($_ < @data) {
    ;
  }
  continue { $_++ }
}

__END__
Results for perl 5.6.1 on FreeBSD 4.6 on a AMD Duron 800, 2002-08-21

Benchmark: timing 100000 iterations of c, perl, perlish, while...
         c:  5 wallclock secs ( 5.21 usr +  0.00 sys =  5.21 CPU) @ 19190.40/s (n=100000)
      perl:  3 wallclock secs ( 2.05 usr +  0.00 sys =  2.05 CPU) @ 48854.96/s (n=100000)
   perlish:  2 wallclock secs ( 2.05 usr +  0.00 sys =  2.05 CPU) @ 48854.96/s (n=100000)
     while:  6 wallclock secs ( 5.78 usr +  0.00 sys =  5.78 CPU) @ 17297.30/s (n=100000)
           Rate   while       c perlish    perl
while   17297/s      --    -10%    -65%    -65%
c       19190/s     11%      --    -61%    -61%
perlish 48855/s    182%    155%      --      0%
perl    48855/s    182%    155%      0%      --