为什么在哈希中向数组追加值也会修改赋值给它的其他变量？ [英] Why is append a value to an array in hash will also modify the other variable that have it assigned?

问题描述

样品的编号：

  hash_of_array = {A：[]} 
B = hash_of_array 
C = hash_of_array 
 
b [：a]<< 1 
 
 puts b＃=> {a：[1]} 
 puts c＃=> {a：[1]} 
  

为什么两个变量在数组中都有1？我只将它附加在变量 b 上。

试过

• Ruby版本2.3.1,2.4.0
  
• Rbenv

解决方案

由于 b 的值和 c 是同一个对象（查看对象＃ object_id ）：



  b.object_id = = c.object_id 
＃=>真
  




Sample code:

hash_of_array = { a: [] }
b = hash_of_array
c = hash_of_array

b[:a] << 1

puts b # => { a: [1] }
puts c # => { a: [1] }

Why do both variable have 1 in their array? I only appended it on variable b.

Tried on

• Ruby Version 2.3.1, 2.4.0
• Rbenv

解决方案

Because value of b and value of c is the same object (check out Object#object_id):

b.object_id == c.object_id
#=> true

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