[Courses] [Ruby] Lesson 0: Installing, References, and your first homework assignment

[Andrea Landaker]

I'm a computer programmer turned stay-at-home-mom, who still loves 
computers.  :-)  Most of my programming these days is simple Ruby scripts for 
myself or for my website (an audio/image gallery program, recoding mp3s, 
etc).  In the past I've used Java, C++, and Scheme, but I'm a big fan of 
Ruby.  I have never really sat down and "learned" it, though -- just started 
ploughing through getting things to work.  So I'm looking forward to learning 
some (probably basic) new things that I hadn't thought I needed but will 
probably be useful.

Not sure if I'll make it through the whole course due to the fact that my 
1-year-old hates me being on the computer (he likes to turn it off), but 
it'll be fun!

OK, for the next part of the homework, here's my husband's interactive 
crytpogram solver:

#!/usr/bin/ruby

$code = ARGV.join(' ').upcase

puts $code
print '$ '
STDOUT.flush
while STDIN.gets
  if ~ /([A-Za-z]{2}).*/
    code = $1[0..0].upcase
    text = $1[1..1].upcase
    $code.gsub!(code,'!')
    $code.gsub!(text,code)
    $code.gsub!('!',text)
  else
    puts "Enter xY to make x -> Y"
  end
  puts $code
  print '$ '
  STDOUT.flush
end

The first line puts all the "arguments" (the cryptogram itself) into the 
global variable "code", uppercased.  It prints it out, and then takes two 
letters from the user.  The first letter goes in the local variable "code", 
and the second goes into "text".  Then, throughout the global variable 
"code", it swaps the two (using the exclamation point for an intermediary 
character).  This repeats essentially forever.

-- 
Andrea Landaker
http://www.icecavern.net/~qirien/