Re^4: Exact string matching

The fastest way to n-tuple long strings is using unpack:

$text = 'howdoidoit';;

print for unpack '(a3X2)*', $text;;
how
owd
wdo
doi
oid
ido
doi
oit
it
it

print for unpack '(a4X3)*', $text;;
howd
owdo
wdoi
doid
oido
idoi
doit
oit
oit
oit
[download]

You have to discard the last n-1 results but that is very quick and simple to do.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Comment on Re^4: Exact string matching Download Code

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Re^5: Exact string matching by AnomalousMonk (Archbishop) on Oct 16, 2011 at 23:29 UTC
... and this approach can easily be extended to make n dynamic by interpolating the width counts in the unpack template string. `>perl -wMstrict -le "my $text = 'howdoidoit'; ;; my $n = 3; my $back = $n - 1; ;; my @unpacked = unpack qq{(a$n X$back)*}, $text; my %count; $count{$_}++ for @unpacked[0 .. $#unpacked - $back]; ;; use Data::Dumper; print Dumper \%count; " $VAR1 = { 'wdo' => 1, 'ido' => 1, 'owd' => 1, 'how' => 1, 'oid' => 1, 'oit' => 1, 'doi' => 2 };` [download]	[reply] [d/l]

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Re^5: Exact string matching
by AnomalousMonk (Archbishop) on Oct 16, 2011 at 23:29 UTC

... and this approach can easily be extended to make n dynamic by interpolating the width counts in the unpack template string.

>perl -wMstrict -le
"my $text = 'howdoidoit';
 ;;
 my $n    = 3;
 my $back = $n - 1;
 ;;
 my @unpacked = unpack qq{(a$n X$back)*}, $text;
 my %count;
 $count{$_}++ for @unpacked[0 .. $#unpacked - $back];
 ;;
 use Data::Dumper;
 print Dumper \%count;
"
$VAR1 = {
          'wdo' => 1,
          'ido' => 1,
          'owd' => 1,
          'how' => 1,
          'oid' => 1,
          'oit' => 1,
          'doi' => 2
        };
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