How can I prevent Perl from interpreting double-backslash as single-backslash character?

Question

How can I print a string (single-quoted) containing double-backslash \\\\ characters as is without making Perl somehow interpolating it to single-slash \\

Answer 1

Since the backslash interpolation happens in string literals, perhaps you could declare your literals using some other arbitrary symbol, then substitute them for something else later.

my $string = 'a!!!b';
$string =~ s{!}{\\}g;
print $string; #prints 'a\\\b'

Of course it doesn't have to be !, any symbol that does not conflict with a normal character in the string will do. You said you need to make a number of strings, so you could put the substitution in a function

sub bs {
    $_[0] =~ s{!}{\\}gr
}

my $string = 'a!!!b';
print bs($string); #prints 'a\\\b'

P.S. That function uses the non-destructive substitution modifier /r introduced in v5.14. If you are using an older version, then the function would need to be written like this

sub bs {
    $_[0] =~ s{!}{\\}g;
    return $_[0];
}

Or if you like something more readable

sub bs {
    my $str = shift;
    $str =~ s{!}{\\}g;
    return $str;
}