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Re^3: finding number of contiguous letters

by Skeeve (Parson)
on May 23, 2007 at 12:31 UTC ( #616990=note: print w/replies, xml ) Need Help??


in reply to Re^2: finding number of contiguous letters
in thread finding number of contiguous letters

I beg to differ...

For this substr based implementation it's important to have the temporary array @parts. For the regex it's unimportant! So if we leave the assignment to the array out, the regex is way faster!

Update: Can this be due to the fact that the functions might be called in a scalar context?

use warnings; use strict; use Benchmark qw(cmpthese); my $str = "Just Another Perl Hacker"; print join " ", do_mapstr (), "\n"; print join " ", do_substr (), "\n"; print join " ", do_regex (), "\n"; print "\n"; cmpthese (-1, { mapstr => \&do_mapstr, substr => \&do_substr, regex => \&do_regex, } ); sub do_mapstr { return map substr($str,$_-3,3),(3..length $str); } sub do_substr { my @parts; push @parts, substr $str, $_, 3 for 0 .. length ($str) - 3; return @parts; } sub do_regex { return $str =~ /(?=(...))/g; }

Result

Jus ust st t A An Ano not oth the her er r P Pe Per erl rl l H H +a Hac ack cke ker Jus ust st t A An Ano not oth the her er r P Pe Per erl rl l H H +a Hac ack cke ker Jus ust st t A An Ano not oth the her er r P Pe Per erl rl l H H +a Hac ack cke ker Rate substr mapstr regex substr 25123/s -- -48% -97% mapstr 48651/s 94% -- -95% regex 1003705/s 3895% 1963% --

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

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