I was wondering whether it made sense to write things like if (index($options,'checkboxes')>-1) {...} instead of if ($options=~/checkboxes/) {...} for speed. So I whipped up this little benchmark: 
#!/usr/bin/perl
# regindbench - which is faster, regexp for fixed text patterns or ind
+ex()?

use strict;
use Benchmark qw/:all/;

sub random { int rand shift }
my @letters=('A'..'Z');
my $nLetters=scalar @letters;
my $text=join('',map { $letters[random($nLetters)] } 0..9999);    # 10
+,000 chars
my ($pat,@pats);
map {
   do {
      $pat=join('',map { $letters[random($nLetters)] } 0..4);  # 5 cha
+r patterns
   } until index($text,$pat)==-1;    # which never match
   push @pats,$pat;
} 0..99;

sub via_regexp {
   map { die "via_regexp $_ found\n" if $text=~/$_/ } @pats;
}

sub via_index {
   map { die "via_index $_ found\n" if index($text,$_)>-1 } @pats;
}

cmpthese(100000,{regexp=>\&via_regexp,index=>\&via_index});

exit;

__END__

Perl 5.8.8 using

100000 iterations on a 3 GHz 64-bit Intel QuadCore
running Fedora Core 7 (6000 bogomips per core)

        Rate  index regexp
index  370/s     --   -47%
regexp 695/s    88%     --

[download]
As you can see, regexp is about twice as fast as using index for running 100 failed matches of fixed text against a single text. I am aware of Regexp::List but wanted to use something which tests unoptimized Perl for really single cases.

If I add study $text, there is a fairly impressive improvement, but then again I'm not going to be using study for every comparison: 

study $text;   # added before call to cmpthese above

         Rate  index regexp
index   364/s     --   -71%
regexp 1274/s   250%     --

[download]
What do my fellow monks think? Shouldn't regexp have more overhead than a simple strstr? Or is this that Magic we keep hearing about? ;-)

SSF

In reply to is index faster than regexp for fixed text token? by sflitman

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.