Re: replace / with \ using regular expressions?

[davorg]

For replacing a single, known character, then regular expressions are the wrong tool. You need the tr/// operator as has already been pointed out.

The difference in performance is impressive:

$ cat bench
#!/usr/bin/perl

use strict;
use warnings;

use Benchmark 'cmpthese';

sub regex_subst {
  $_ = 'this/is/a/string';
  s|/|\\|g;
}

sub tr_subst {
  $_ = 'this/is/a/string';
  tr|/|\\|;
}

cmpthese(1_000_000, {
          s  => \&regex_subst,
          tr => \&tr_subst,
         });
$ ./bench
        Rate    s   tr
s   287356/s   -- -75%
tr 1162791/s 305%   --
$

[Juerd]

You need the tr/// operator

No, you don't need it. TIMTOWTDI, and s///g is as understandable and easy to write just like tr///.

The difference in performance is impressive

But typically completely irrelevant for the performance of scripts/programs of any size. This optimization feels pretty immature.

When will doing 287356 of these operations per second ever be anything other than fast enough?

[Anonymous Monk]

hi daveorg, Thanks for making this clear to me.

[Marshall]

I would just point out that the Perl functions on Windows don't care about / vs \. If you calling a Perl function leave it in a/b/xyz format. Of course a command to the Windows shell is different.