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%   --
$

[download]
--

See the Copyright notice on my home node.

Perl training courses

In reply to Re: replace / with \ using regular expressions? by davorg
in thread replace / with \ using regular expressions? by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.