string manipulation
in [Perl]
|
From: Ch Lamprecht on 29 Jan 2006 10:37 James Taylor schrieb: > Tad McClellan <tadmc(a)augustmail.com> wrote: > > >>James Taylor <usenet(a)oakseed.demon.co.uk.invalid> wrote: >> >> >>>my ($dir, $leaf) = $path =~ m|^(.*)/(.*)|; >> >> ^ >> ^ >> >>That anchor serves no useful purpose, so it probably shouldn't be there. > > The reason it is there is to ensure that the match fails in > linear time if there is no slash in the $path. > However, for strings without slashes, the pattern with the anchor will be (a little) slower than without the anchor. (If anybody want's to know ;) ) use warnings; use strict; use Benchmark qw(cmpthese) ; my $string = "a_string_with_or_without_slashes"; my $string2 = "a_string_with_or/without_slashes"; cmpthese(1000000, { 'anchor' => sub{my($foo,$bar)=$string =~ m|^(.*)/(.*)|}, 'no_anchor' => sub{my($foo,$bar)=$string =~ m|(.*)/(.*)|}, 'an+/' => sub{my($foo,$bar)=$string2 =~ m|^(.*)/(.*)|}, 'no_an+/' => sub{my($foo,$bar)=$string2 =~ m|(.*)/(.*)|} }); prints: Rate no_an+/ an+/ anchor no_anchor no_an+/ 275028/s -- -1% -83% -84% an+/ 278164/s 1% -- -83% -84% anchor 1636661/s 495% 488% -- -5% no_anchor 1721170/s 526% 519% 5% -- Btw: Is there an expression like 'peacounting' in english ?? Christoph -- please reply to perl -e "print scalar reverse q/ed.bew(a)thcerpmal.hpotsirhc/"
From: Ch Lamprecht on 29 Jan 2006 10:38 James Taylor schrieb: > Tad McClellan <tadmc(a)augustmail.com> wrote: > > >>James Taylor <usenet(a)oakseed.demon.co.uk.invalid> wrote: >> >> >>>my ($dir, $leaf) = $path =~ m|^(.*)/(.*)|; >> >> ^ >> ^ >> >>That anchor serves no useful purpose, so it probably shouldn't be there. > > The reason it is there is to ensure that the match fails in > linear time if there is no slash in the $path. > However, for strings without slashes, the pattern with the anchor will be (a little) slower than without the anchor. (If anybody want's to know ;) ) use warnings; use strict; use Benchmark qw(cmpthese) ; my $string = "a_string_with_or_without_slashes"; my $string2 = "a_string_with_or/without_slashes"; cmpthese(1000000, { 'anchor' => sub{my($foo,$bar)=$string =~ m|^(.*)/(.*)|}, 'no_anchor' => sub{my($foo,$bar)=$string =~ m|(.*)/(.*)|}, 'an+/' => sub{my($foo,$bar)=$string2 =~ m|^(.*)/(.*)|}, 'no_an+/' => sub{my($foo,$bar)=$string2 =~ m|(.*)/(.*)|} }); prints: Rate no_an+/ an+/ anchor no_anchor no_an+/ 275028/s -- -1% -83% -84% an+/ 278164/s 1% -- -83% -84% anchor 1636661/s 495% 488% -- -5% no_anchor 1721170/s 526% 519% 5% -- Btw: Is there an expression like 'peacounting' in english ?? Christoph -- please reply to perl -e "print scalar reverse q/ed.bew(a)thcerpmal.hpotsirhc/"
From: James Taylor on 29 Jan 2006 11:34 Ch Lamprecht <christoph.lamprecht.no.spam(a)web.de> wrote: > Btw: Is there an expression like 'peacounting' in english ?? Yes, almost the same, it's "bean counting". -- James Taylor
First
|
Prev
|
Pages: 1 2 3 4 Prev: Check subroutine-specific requirements on module import Next: Java sucks, Perl Rules. |