在 Ruby 中反转字符串 [英] Reverse a string in Ruby

问题描述

如何在 Ruby 中反转字符串?我知道字符串#reverse.我有兴趣了解如何用纯 Ruby 编写它，最好是就地解决方案.

How do you reverse a string in Ruby? I know about string#reverse. I'm interested in understanding how to write it in pure Ruby, preferably an in-place solution.

推荐答案

已经有一个 inplace reverse 方法，叫做reverse！":

There's already an inplace reverse method, called "reverse!":

$ a = "abc"
$ a.reverse!
$ puts a
cba

如果您想手动执行此操作，请尝试此操作(但它可能不是多字节安全的，例如 UTF-8)，它会更慢:

If you want to do this manually try this (but it will probably not be multibyte-safe, eg UTF-8), and it will be slower:

class String
  def reverse_inplace!
    half_length = self.length / 2
    half_length.times {|i| self[i], self[-i-1] = self[-i-1], self[i] }
    self
  end
end

这会将开头的每个字节与结尾的每个字节交换，直到两个索引在中心相遇:

This swaps every byte from the beginning with every byte from the end until both indexes meet at the center:

$ a = "abcd"
$ a.reverse_inplace!
$ puts a
dcba

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