Ruby 标准库实用指南：功能与应用详解
1. Set 库
Set 是一个用于存储唯一值的集合，其唯一性通过eql?和hash方法确定。以下是一些基本操作示例：
require 'set' set1 = Set.new([:bear, :cat, :deer]) puts set1.include?(:bat) # false set1.add(:fox) puts set1 # #<Set: {:cat, :deer, :fox, :bear}> partition = set1.classify {|element| element.to_s.length } puts partition # {3=>#<Set: {:cat, :fox}>, 4=>#<Set: {:deer, :bear}>} set2 = [ :cat, :dog, :cow ].to_set puts set1 | set2 # #<Set: {:cat, :dog, :deer, :cow, :fox, :bear}> puts set1 & set2 # #<Set: {:cat}> puts set1 - set2 # #<Set: {:deer, :fox, :bear}> puts set1 ^ set2 # #<Set: {:dog, :deer, :cow, :fox, :bear}>还可以对/etc/passwd
