my @find = map { [ split // ] }qw ( ABCDE FGHJJ KLMMM );
my $find_len = 5;
my $fuzzy    = 2;

while( my $search = <DATA>) {
    chomp $search;
    # this should be in C with pointers for speed, not messing with perl arrays
    my $search = [split //, $search];
    for my $i ( 0..@$search-$find_len ) {
        FIND:
        for my $find ( @find ) {
            my $misses = 0;
            for my $j ( 0..$find_len-1 ) {
                $misses++ if $search->[$i+$j] ne $find->[$j];
                next FIND if $misses > $fuzzy;
            }
            print "Str $. Match ($misses) miss for @$find at $i\n";
        }
    }
}  


__DATA__
ABCDEFGHIJKLMNOPQRSTUVWXYZ
AAABBCDEFGHIJKLMN