Perl | Print ASCII, but backslashed other

Question

I want print 95 ASCII symblols unchanged, but for others to print its codes. How make it in pure perl? 'unpack' function? Any module?

print BackSlashed('test folder'); # expected test\040folder

print BackSlashed('test тестовая folder'); 
# expected test\040\321\202\320\265\321\201\321\202\320\276\320\262\320\260\321\217\040folder

print BackSlashed('НОВАЯ ПАПКА');
# expected \320\235\320\236\320\222\320\220\320\257\040\320\237\320\220\320\237\320\232\320\220

sub BackSlashed() {
my $str = shift;
.. backslashed code here...
return $str
}

Answer 1

You can use a regular expression substitution with an evaled substitution part. In there, need to convert each character to its numeric value first, and then output it in octal notation. There's a good explanation for it in this answer. Attach an escaped backslash \ to get it to show up in the output.

$str =~ s/([^a-zA-Z0-9])/sprintf "\\%03o", ord($1)/eg;

I limited the capture group to basic ASCII letters and numbers. If you want something else, just change the character group.

---

Since your sample output has octets but you said your code has the use utf8 pragma, you need to convert Perl's representation of the string to the corresponding octet sequence before you run the substitution.

use utf8;
my $str = 'НОВАЯ ПАПКА';
print foo($str);

sub foo { # note that there are no () here!
    my $str = shift;
    utf8::encode($str);
    $str =~ s/([^a-zA-Z0-9])/sprintf "\\%03o", ord($1)/eg;
    return $str;
}