<voice type="marvin_the_martian">Greetings earth specimen. You have made a naughty Benchmark goof, so I shall have to blow you up</voice> ;-)

Note that $var is modified by the subs, so calling them over and over again is pointless. This is very misleading because the "work" you are attempting to benchmark is only being done once. Your tests essentially behave like this:

$var = 'abc';
$var =~ s/b//; # $var is now 'ac'
$var =~ s/b//; # still 'ac' even before the s///
$var =~ s/b//; # yet another attempt to remove 'b' from 'ac'
$var =~ s/b//; # well, you get the point....
.... etc.
[download]

Here is a better benchmark (on 5.6.0) that restores my faith in tr///:

#!/usr/bin/perl -wT

use strict;

use Benchmark;
our $var;

$var = '\a\\aa\\\aaa\\\\aaaa'x100;

## rerun the original benchmarks to provide a baseline 
timethese(100000, {
    'old s'  => sub { $var =~ s/\\//g },
    'old tr' => sub { $var =~ tr/\\//d },
});

## try some new benchmarks that reinitialize $var each time
timethese(50000, {
    'new s'  => sub { $var = '\a\\aa\\\aaa\\\\aaaa'x100; $var =~ s/\\/
+/g },
    'new tr' => sub { $var = '\a\\aa\\\aaa\\\\aaaa'x100; $var =~ tr/\\
+//d },
});

=OUTPUT
Benchmark: timing 100000 iterations of old s, old tr...
     old s:  1 wallclock secs ( 0.56 usr +  0.00 sys =  0.56 CPU) @ 17
+8571.43/s (n=100000)
    old tr:  2 wallclock secs ( 1.23 usr +  0.00 sys =  1.23 CPU) @ 81
+300.81/s (n=100000)
Benchmark: timing 50000 iterations of new s, new tr...
     new s: 43 wallclock secs (30.81 usr +  0.02 sys = 30.83 CPU) @ 16
+21.80/s (n=50000)
    new tr:  3 wallclock secs ( 2.06 usr +  0.00 sys =  2.06 CPU) @ 24
+271.84/s (n=50000)
[download]

-Blake

---

---

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.