在迭代时添加到数组 [英] Adding to an Array while Iterating

问题描述

为什么这段代码'锁定'红宝石？什么是超越它的最佳方式？我在下面发布了解决方案。还有另一种方法吗？提前致谢！

Why does this code 'lock up' ruby? And what is the best way to get past it? I posted my solution below. Is there another way to do this? Thanks in advance!

代码：

nums = [1, 2, 3] 
nums.each { |i| nums << i + 1 }

我的解决方案：

nums = [1, 2, 3]
adjustments = []
nums.each { |i| adjustments << i + 1 }
nums += adjustments 

推荐答案

那是因为每个人都使用一个枚举器（所以如果你继续添加它就永远不会到达终点）。

That's because each uses an enumerator (so it never reaches the end if you keep adding to it).

你可以在应用每个数组之前复制数组。

You can duplicate the array before applying each.

nums = [1, 2, 3] 
nums.dup.each { |i| nums << i + 1 }

另一种方法是追加map给出的额外元素：

Another way is to append the extra elements given by map:

nums = [1, 2, 3] 
nums += nums.map { |i|  i + 1 }

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