h1 = Hash.new             #默认值为nil
h2 = Hash.new(“This is my first hash instance”) #默认值为” This is my first hash instance”:

h2["one"] = "北京"
h2["two"] = "上海"
h2["three"] = "深圳"
h2["four"] = "广州"

h2 = {
"one" => "北京",
"two" =>"上海",
"three" =>"深圳",
"four" =>"广州" 
}

　　puts h2[“one”]    #=>”北京”

  　　puts h1.default
  　　h1.default += “This is set value method”

  h3 = h2
  h3[“one”] = “西安”
  puts h h2[“one”]    #=>”西安”

  h4 = h2.clone
  h4[“one”] = “大连”
  puts h2[“one”]       #=>”西安”（i.e. 值没有修改）

  def sorted_hash(aHash)
    return aHash.sort{
      |a,b| a.to_s <=> b.to_s      
    }
  End
h1 = {1=>'one', 2=>'two', 3=> 'three'}
h2 = {6=>'six', 5=>'five', 4=> 'four'}
h3 = {'one'=>'A', 'two'=>'B','three'=>'C'}
h4 = h1.merge(h2)      #合并hash
h5 = h1.merge(h3)
def sorted_hash(aHash)
 return aHash.sort{|a,b| a.to_s <=> b.to_s }
end
p(h4)     
p(h4.sort)
p(h5)
p(sorted_hash(h5))

{5=>"five", 6=>"six", 1=>"one", 2=>"two", 3=>"three", 4=>"four"}
[[1, "one"], [2, "two"], [3, "three"], [4, "four"], [5, "five"], [6, "six"]]
{"two"=>"B", "three"=>"C", 1=>"one", 2=>"two", "one"=>"A", 3=>"three"}
[[1, "one"], [2, "two"], [3, "three"], ["one", "A"], ["three", "C"], ["two", "B"]]

  student = {
     "name" => "Steve",
     "age" => 22,
     "Gender" => "male"
    }  
  p student.keys              #=> ["name", "Gender", "age"]
  p student.values            　#=> ["Steve", "male", 22]
  puts student.include?("age")       　 #=> true
  puts student.size             #=> 3
  student.delete("Gender")
  puts student.has_key?("Gender")       #=>false
  puts student.size             #=>2

class HashObj
 class << self
 def load_from_hash(hash)
  if hash.instance_of? Hash
  obj = HashObj.new
  hash.each{|k,v| obj.send :def_sget_method,k,HashObj.load_from_hash(v)}
  obj
  elsif hash.instance_of? Array
  hash.map{|m| HashObj.load_from_hash(m) }
  else
  hash
  end
 end
 end

 def attributes
 hash = {}
 @@reg ||= /=/
 self.singleton_methods.reject{|x| @@reg =~ x.to_s}.each do |m|
  v = self.send(m)
  if v.instance_of? HashObj
  real_v = v.attributes
  elsif v.instance_of? Array
  real_v = []
  v.each do |l|
   if l.instance_of? HashObj
   real_v << l.attributes
   else
   real_v << l
   end
  end
  else
  real_v = v
  end
  hash[m] = real_v
 end
 hash
 end

 protected
 def def_sget_method(name,val)
 self.instance_variable_set "@#{name}",val

 self.define_singleton_method "#{name}=" do |n_val|
  instance_variable_set "@#{name}",n_val
 end

 self.define_singleton_method name do
  instance_variable_get "@#{name}"
 end
 end
end

hash = {name:'jack',age:22,phone:['61900871','8787876'],
    basic_info:{country:'USA',city:'New York'}}
obj = HashObj.load_from_hash hash
obj.name #'jack'
obj.age  #22
obj.phone #['61900871','8787876']
obj.basic_info #<HashObj:0x007f9eda02b360 @country="USA", @city="New York">
obj.basic_info.country #'USA'
obj.attributes == hash #true
obj.age = 30
obj.attributes #{:name=>"jack", :age=>30, :phone=>["61900871", "8787876"],
# :basic_info=>{:country=>"USA", :city=>"New York"}}