ruby interview question

Question

I got this question in a previous interview and couldnt do it , any idea?

1. What does this do:

   `$=`;$_=\%!;($_)=/(.)/;$==++$|;($.,$/,$,,$\,$",$;,$^,$#,$~,$*,$:,@%)=( 
   $!=~/(.)(.).(.)(.)(.)(.)..(.)(.)(.)..(.)......(.)/,$"),$=++;$.++;$.++; 
   $_++;$_++;($_,$\,$,)=($~.$"."$;$/$%[$?]$_$\$,$:$%[$?]",$"&$~,$#,);$,++ 
   ;$,++;$^|=$";`$_$\$,$/$:$;$~$*$%[$?]$.$~$*${#}$%[$?]$;$\$"$^$~$*.>&$=` 
   

Answer 1

I am not a Ruby expert by any means by the first step should be make it into a format you can read. I broke it down by line.

`$=`;

$_=\%!;

($_)=/(.)/;

$==++$|;

($.,$/,$,,$\,$",$;,$^,$#,$~,$*,$:,@%)=($!=~/(.)(.).(.)(.)(.)(.)..(.)(.)(.)..(.)......(.)/,$"),$=++;$.++;$.++; 

$_++;

$_++;

($_,$\,$,)=($~.$"."$;$/$%[$?]$_$\$,$:$%[$?]",$"&$~,$#,);

$,++;

$,++;

$^|=$";

`$_$\$,$/$:$;$~$*$%[$?]$.$~$*${#}$%[$?]$;$\$"$^$~$*.>&$=`

I cheated and tried to run it, and it doesn't work. I get an unexpected null error.

Don't feel bad if you can't do this. This seems pointless. Programming questions should try to test your skills not test you on something that if somebody is really using it would mean there application would be really bad.

Answer 2

Here, I changed all the special Ruby globals into single-letter variables and inserted some whitespace:

`a`
n = \%!
(n) = /(.)/
a = ++o
(b, c, d, f, e, g, h, i, j, k, l, @%) = (m =~ /(.)(.).(.)(.)(.)(.)..(.)(.)(.)..(.)......(.)/, e), a++
b++
b++
n++
n++
(n, f, d) = (j . e . "gcp[q]nfdlp[q]", e & j, i,)
d++
d++
h |= e
`nfdclgjkp[q]bjk${#}p[q]gfehjk.>&a`

Whoever wrote this doesn't understand Ruby. There's no increment operator in Ruby. Tokens like \%! and @% mean nothing in Ruby. You can't interpolate variables, even global variables, in strings or backquoted commands, as in "$=". The dot . is not a concatenation operator in Ruby. I don't think this is Ruby. It's like a hybrid of languages.

Answer 3

This looks closer to Perl, to be honest, but in any case pretty nonsensical.

Answer 4

This is Perl code that prints out "Just another Perl hacker."

While most of the $_, $=, etc. variables are available in Ruby as well, the presence of statements such as $,++ indicate Perl, which actually has pre- and post-increment operators, unlike Ruby.

---

I went in with Vim and replaced all the symbols with their English equivalent. I munged something up since the output is now "Just another Per hacker" (missing the L on Perl), but here's what I came up with:

use English;
`$FORMAT_LINES_PER_PAGE`;
$ARG=\%!;($ARG)=/(.)/;$FORMAT_LINES_PER_PAGE=++$OUTPUT_AUTOFLUSH;
($INPUT_LINE_NUMBER,$/,$OUTPUT_FIELD_SEPARATOR,$OUTPUT_RECORD_SEPARATOR,$LIST_SEPARATOR,$SUBSCRIPT_SEPARATOR,$FORMAT_TOP_NAME,$OFMT,$FORMAT_NAME,$MULTILINE_MATCHING,$FORMAT_LINE_BREAK_CHARACTERS,@%)=(
$!=~/(.)(.).(.)(.)(.)(.)..(.)(.)(.)..(.)......(.)/,$LIST_SEPARATOR),$FORMAT_LINES_PER_PAGE++;
$INPUT_LINE_NUMBER++;
$INPUT_LINE_NUMBER++; $ARG++;$ARG++;
($ARG,$OUTPUT_RECORD_SEPARATOR,$OUTPUT_FIELD_SEPARATOR)=($FORMAT_NAME.$LIST_SEPARATOR."$SUBSCRIPT_SEPARATOR$/$FORMAT_PAGE_NUMBER[$CHILD_ERROR]$ARG$OUTPUT_RECORD_SEPARATOR$OUTPUT_FIELD_SEPARATOR$FORMAT_LINE_BREAK_CHARACTERS$FORMAT_PAGE_NUMBER[$CHILD_ERROR]",$LIST_SEPARATOR&$FORMAT_NAME,$OFMT,);
$OUTPUT_FIELD_SEPARATOR++ ;
$OUTPUT_FIELD_SEPARATOR++;
$FORMAT_TOP_NAME|=$LIST_SEPARATOR;
`$ARG$OUTPUT_RECORD_SEPARATOR$OUTPUT_FIELD_SEPARATOR$/$FORMAT_LINE_BREAK_CHARACTERS$SUBSCRIPT_SEPARATOR$FORMAT_NAME$MULTILINE_MATCHING$FORMAT_PAGE_NUMBER[$CHILD_ERROR]$INPUT_LINE_NUMBER$FORMAT_NAME$MULTILINE_MATCHING${#}$FORMAT_PAGE_NUMBER[$CHILD_ERROR]$SUBSCRIPT_SEPARATOR$OUTPUT_RECORD_SEPARATOR$LIST_SEPARATOR$FORMAT_TOP_NAME$FORMAT_NAME$MULTILINE_MATCHING.>&$FORMAT_LINES_PER_PAGE`