Tell us about the larger picture. There is likely to be room for improving whatever you are doing at present, or at least for us to target solutions to whatever the bigger problem is. Most gains in performance are not obtained by micro-optimizations such as you are asking for. Some tricks that will give huge performance gains in some situations will cripple the code in other situations.

That said, you can build masks then xor the strings to give something like the fast match you are looking for where the strings to be matched are fairly long. Consider:

use strict; use warnings; my $strA = 'ATGNCNC'; my $strB = 'ATGACNN'; my $strC = 'TTGACNN'; print $strA, (match ($strA, $strB) ? ' eq' : ' ne'), " $strB\n"; print $strA, (match ($strA, $strC) ? ' eq' : ' ne'), " $strC\n"; sub match { my ($mask1, $mask2) = @_; my ($str1, $str2) = @_; $mask1 =~ tr/NATGC/0\xFF/; $mask2 =~ tr/NATGC/0\xFF/; $mask1 &= $mask2; $str1 ^= $str2; $str1 &= $mask1; return $str1 !~ /[^\x00]/; }



If you can cache the masks (say you were matching all strings against all others for example) then you get a greater gain.

True laziness is hard work

In reply to Re: simple string comparison for efficiency by GrandFather
in thread simple string comparison for efficiency by CaptainF

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, 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, 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.