From: Todd Benson <caduceass@...>
Date: 2008-03-17T19:32:47+09:00
Subject: Re: Cipher

On Mon, Mar 17, 2008 at 5:21 AM, Todd Benson <caduceass@gmail.com> wrote:
> On Sun, Mar 16, 2008 at 9:00 PM, Todd Benson <caduceass@gmail.com> wrote:
>  >
>
> > On Sun, Mar 16, 2008 at 7:50 PM, Max Zhou <ball908765@yahoo.com> wrote:
>  >  > I am trying to make a program that takes what you input, and encrypts it by turning a to p, b to q, z to b, etc.  It moves the letter 2 spaces to the left (a to c) and moves it down (c to p).  (See below.)  Even though you can just say that a will be n, how do you seperate each letter and turn it into a string?  Please put it in terms that a Ruby beginner would understand.
>  >  >   abcdefghijklm
>  >  >   nopqrstuvwxyz
>  >  >
>  >  >
>  >  >
>  >  >  ---------------------------------
>
>  Just for fun, I revisited this.  To include the printable characters
>  on an english-based system (ASCII codes 32 through 126), not including
>  tab, return, line-feed, etc...
>
>
>  puts str = "Hello, world! Yabba dabba doo!"
>  puts
>
>  char_set = (32..126).map.pack('c*')
>  start, finish, offset = ?a, ?p, ?p - ?a
>  puts "char_set:\n" + char_set = (?\s..?~).map.pack('c*')
>  puts
>
>  size = char_set.size
>  new_str = ""
>  str.each_byte do |byte|
>   new_str << char_set[(byte + offset - char_set[0]) % size]
>  end
>  puts "enciphered: \n" + new_str

Dang it!  Another thing that unit tests won't catch: code that is
redundant!  Removing the first "char_set =" line will have the same
result...

puts str = "Hello, world! Yabba dabba doo!"
puts

start, finish, offset = ?a, ?p, ?p - ?a
puts "char_set:\n" + char_set = (?\s..?~).map.pack('c*')
puts

size = char_set.size
new_str = ""
str.each_byte do |byte|
  new_str << char_set[(byte + offset - char_set[0]) % size]
end
puts "enciphered: \n" + new_str


Todd