Ruby 从哈希表中弹出一个元素？

Question

我正在查看 http://ruby-doc.org/core-1.9.3/Hash.html而且似乎没有 pop 方法？我想我错过了一些东西......

if (x = d['a']) != nil
  d.delete('a') 
end

Answer 1

如果知道key，直接delete就可以了如果散列不包含 key ，您将返回 nil，否则您将获得存储在那里的任何内容

来自您链接到的文档:

h = { "a" => 100, "b" => 200 }
h.delete("a")                              #=> 100
h.delete("z")                              #=> nil
h.delete("z") { |el| "#{el} not found" }   #=> "z not found"

还有一种删除并返回键值对的shift:

hsh = Hash.new

hsh['bb'] = 42
hsh['aa'] = 23
hsh['cc'] = 65

p hsh.shift

=> ["bb", 42]

可以看出，哈希的顺序是插入的顺序，而不是键或值。来自文档

Hashes enumerate their values in the order that the corresponding keys were inserted.