Update: realized this is the same idea as tachyon's Re: Fuzzy Searching: Optimizing Algorithm Selection

How about something simple minded: for each substring of the target, compute the difference with the search string, if the diff is less than 3, accept it. This will only find out matches that have at most two letter difference (but not missing):

use strict;
 
my $search = "apple";
my $length = 5;  #length of the target
my $FUZZY = 2; #
my $BIG = 10;
while(my $a = <DATA>){
        chomp $a;
        my $score = $BIG;
        for(my $i = 0; $i + $length < length($a); $i++){
                $score = diff_score($search, substr($a,,$i,$length));
                if($score <= $FUZZY){
                        print "$score: $a\n";
                        last;
                }
        }
        if($score > $FUZZY){
                print "-1:$a\n";
        }
}
 
# return the number of different letters.
sub diff_score{
        my ($first, $second)= @_;

        return $BIG unless length($first) == length($second);
        my $score = 0;
        for(my $i = 0; $i < length($first); ++$i){
                ++$score if substr($first,$i,1) ne substr($second,$i,1
+);
        }
        return $score;
}
         
 
 
 
__DATA__
This is an apple
An arple is here
What bpple is that
What  is that
What bple is that
aplle is not a word
[download]

Output as follows, diffs are in front, -1 show not matching fuzzily.

__OUTPUT__
0: This is an apple
1: An arple is here
1: What bpple is that
-1:What  is that
2: What bple is that
1: aplle is not a word
[download]

---

---

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.