7、Ruby 编程：回文检测与文本换行符转换

Ruby 编程：回文检测与文本换行符转换

1. 回文检测

1.1 简单回文检测思路

字符串可以反转自身，而回文串的定义是其反转后与自身相同。不过，简单的回文检测并不令人完全满意，比如对于一些包含非字母字符的句子就不适用，所以需要更复杂的回文检测方法。

1.2 复杂回文检测实现（ palindrome2.rb ）

#!/usr/bin/env ruby
# palindrome2.rb
=begin rdoc
Gives every <b>String</b> the ability to identify whether it is a 
a palindrome. This version ignores all non-alphabetic characters,
making it suitable for longer text items.
=end
class String
  DUAL_CASE_ALPHABET = ('a'..'z').to_a + ('A'..'Z').to_a
=begin rdoc
Contrast this with some other languages, involving iterating through each
string index and comparing with the same index from the opposite end.
Takes 1 optional Boolean, which indicates whether case matters. 
Assum