http://qs1969.pair.com?node_id=11134023


in reply to Re^3: Windows and backslashes and replacements oh my!
in thread Windows and backslashes and replacements oh my!

One $bs is sufficient in my tests:

d:\>perl -E"for $x (qw/C:\berrybrew\test C:\berrybrew /) {$_=$x; $bs=c +hr(92); s/berrybrew(?!\\+test)/berrybrew${bs}test/; say}" C:\berrybrew\test C:\berrybrew\test d:\>

> Obviously Perl needs to escape the backslash inside a regex

not after interpolation of variables like $bs

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

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Re^5: Windows and backslashes and replacements oh my! (two escapings in LHS of s///)
by LanX (Sage) on Jun 19, 2021 at 12:09 UTC
    > > Obviously Perl needs to escape the backslash inside a regex

    > not after interpolation of variables like $bs

    I have to correct myself, it depends on the side of the substitution

    • the right side is a simple doublequoted string, so after interpolation no escaping
    • but the left side is a regex with two levels of escaping
      1. string interpolation with escaping first, i.e. \$bs won't be interpolated
      2. regex interpretation with escaping first, i.e. /\*/ is not a quantifier but literal * same with /$bs*/
    compare
    d:\>perl -E"for $x (qw/C:\berrybrew\test C:\berrybrew /) {$_=$x; $bs=c +hr(92); s#$bs$bs#<${bs}>#g; say}" C:<\>berrybrew<\>test C:<\>berrybrew d:\>

    or to eliminate the Win command line

    use v5.12; use warnings; use Data::Dump; my $bs=chr(92); for my $x (qw/C:\berrybrew\test C:\berrybrew /) { $_=$x; s#$bs$bs#<${bs}>#g; say; #ddx $_; } $_='$bs'; s/\$bs/<$&>/; say;
    C:<\>berrybrew<\>test C:<\>berrybrew <$bs>
    so this might be the OPs original problem

    see also

    s/RegEx/substitutions/: Variable interpolation and when to use /e - modifiers

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery