Reverse a string in Ruby

Question

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.

Answer 1

Here's one way to do it with inject and unshift:

"Hello world".chars.inject([]) { |s, c| s.unshift(c) }.join

Answer 2

"abcde".chars.reduce{|s,c| c + s }          # => "edcba"

Answer 3

A simple classic way with n/2 complexity

str = "Hello World!";
puts str;

for i in 0..(str.length/2).to_i
  mid = (str.length-1-i);
  temp = str[i];
  str[i] = str[aa];
  str[aa] = temp;
end

puts str;

Answer 4

Here's an alternative using the xor bitwise operations:

class String

  def xor_reverse
    len = self.length - 1
    count = 0

    while (count < len)
      self[count] ^= self[len]
      self[len] ^= self[count]
      self[count] ^= self[len]

      count += 1
      len -= 1
    end

  self
end

"foobar".xor_reverse
=> raboof

Answer 5

def reverse(string)
reversed_string = ""

idx = 0
while idx < string.length
reversed_string = string[idx] + reversed_string
idx += 1
end

return reversed_string
end

Answer 6

def palindrome(string)

  s = string.gsub(/\W+/,'').downcase

  t = s.chars.inject([]){|a,b| a.unshift(b)}.join

  return true if(s == t)

  false

end