Yes, you're right, with many consecutive quotes, s/"+//g would be considerably faster than s/"//g.

Here are a few benchmarks for those of you who like performance tuning for the sake of performance tuning... :)

As can be seen easily, in the extreme (unrealistic) case with 999 consecutive quotes followed by a single other character, s/"+//g clearly wins, while with more realistic cases, the difference between the s/// variants becomes less pronounced, and tr/"//d is outperforming both of them. 

#!/usr/bin/perl
use strict;
use warnings; no warnings "numeric" ;
use Benchmark "cmpthese";

my %strings = (
    '999:1' => scalar ('"' x 999 . '-') x 1000,
    '9:1'   => '"""""""""-' x 100000,
    '1:1'   => '"-' x 500000,
);

for my $test (sort {$b<=>$a} keys %strings) {
    my $s = $strings{$test};
    printf "\n%s... ($test):\n\n", substr($s,0,30);

    cmpthese (1000,
    {
        's/"//g'  => sub {
                      my $t = $s;
                      $t =~ s/"//g;
                  },
        's/"+//g' => sub {
                      my $t = $s;
                      $t =~ s/"+//g;
                  },
        'tr/"//d' => sub {
                      my $t = $s;
                      $t =~ tr/"//d;
                  },
    } );
}

[download]

___

$ ./700801.pl

""""""""""""""""""""""""""""""... (999:1):

          Rate  s/"//g tr/"//d s/"+//g
s/"//g  4.09/s      --    -98%    -99%
tr/"//d  212/s   5079%      --    -31%
s/"+//g  309/s   7445%     46%      --

"""""""""-"""""""""-"""""""""-... (9:1):

          Rate  s/"//g s/"+//g tr/"//d
s/"//g  4.49/s      --    -85%    -98%
s/"+//g 30.7/s    584%      --    -83%
tr/"//d  181/s   3931%    490%      --

"-"-"-"-"-"-"-"-"-"-"-"-"-"-"-... (1:1):

          Rate s/"+//g  s/"//g tr/"//d
s/"+//g 6.78/s      --    -16%    -97%
s/"//g  8.05/s     19%      --    -96%
tr/"//d  211/s   3005%   2515%      --

[download]

(results shown for "perl, v5.8.8 built for x86_64-linux-thread-multi", but v5.10.0 behaves similarly)

In reply to Re^4: eliminate quotes by almut
in thread eliminate quotes by quasimodem

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