From: "Peña, Botp" <botp@...>
Date: 2008-05-27T13:57:21+09:00
Subject: Re: string+char, cant convert nil, but not nil

From: notnorwegian@yahoo.se [mailto:notnorwegian@yahoo.se] 
# tryong to do a ROT13(http://en.wikipedia.org/wiki/Rot_13) encrypter/
# decrypter.
# x = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
# y = "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm"
# arr = x.split(//).zip(y.split(//))
# dict = Hash[*arr.flatten]
# puts "Input phrase: "
# phrase = gets

if you tried this in irb, you'd see the value of phrase. 
hint: gets also stores the (unwanted) ending char 
(chomp the newline pls :)

# rotated = ""
# for x in (0..phrase.length()-1)
#         rotated = rotated + dict[phrase[x].chr]
# end
# puts rotated
# 
# '+' cant convert nil into string
# cant convert nil into string

that's the effect

dict["\n"]
#=> nil

btw, in ruby, there are many ways to skin that rot13 problem.

eg,

"testing".tr('A-MN-Za-mn-z','N-ZA-Mn-za-m')
#=> "grfgvat"

kind regards -botp