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”

copy
    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

h1 = {1=>'one', 2=>'two', 3=> 'three',4=> 'four'}
h2 = {1=>'one', 3=>'two', 4=> 'four',5=> 'five'}
 
p( h1.keys & h2.keys )
p( h1.values & h2.values )
p( h1.keys+h2.keys )
p( h1.values-h2.values )
p( (h1.keys << h2.keys) )
p( (h1.keys << h2.keys).flatten)

[1, 3, 4]
["one", "two", "four"]
[1, 2, 3, 4, 5, 1, 3, 4]
["three"]
[1, 2, 3, 4, [5, 1, 3, 4]]
[1, 2, 3, 4, 5, 1, 3, 4]

  a=[1,2,3]
  b=[4,5,6]
 
  p(a+b)
  p(a<<b)

[1, 2, 3, 4, 5, 6]
[1, 2, 3, [4, 5, 6]]     #[1, 2, 3, [4, 5, 6]].flatten =>[1, 2, 3, 4, 5, 6]