How to generate a random string in Ruby

Question

I'm currently generating an 8-character pseudo-random uppercase string for "A" .. "Z":

value = ""; 8.times{value  << (65 + rand(25)).chr}

but it doesn't look clean, and it can't be passed as an argument since it isn't a single statement. To get a mixed-case string "a" .. "z" plus "A" .. "Z", I changed it to:

value = ""; 8.times{value << ((rand(2)==1?65:97) + rand(25)).chr}

but it looks like trash.

Does anyone have a better method?

Answer 1

My 2 cents:

  def token(length=16)
    chars = [*('A'..'Z'), *('a'..'z'), *(0..9)]
    (0..length).map {chars.sample}.join
  end

Answer 2

I like Radar's answer best, so far, I think. I'd tweak a bit like this:

CHARS = ('a'..'z').to_a + ('A'..'Z').to_a
def rand_string(length=8)
  s=''
  length.times{ s << CHARS[rand(CHARS.length)] }
  s
end

Answer 3

With this method you can pass in an abitrary length. It's set as a default as 6.

def generate_random_string(length=6)
  string = ""
  chars = ("A".."Z").to_a
  length.times do
    string << chars[rand(chars.length-1)]
  end
  string
end

Answer 4

Array.new(n){[*"0".."9"].sample}.join, where n=8 in your case.

Generalized: Array.new(n){[*"A".."Z", *"0".."9"].sample}.join, etc. - from this answer

Answer 5

Others have mentioned something similar, but this uses the URL safe function.

require 'securerandom'
p SecureRandom.urlsafe_base64(5) #=> "UtM7aa8"
p SecureRandom.urlsafe_base64 #=> "UZLdOkzop70Ddx-IJR0ABg"
p SecureRandom.urlsafe_base64(nil, true) #=> "i0XQ-7gglIsHGV2_BNPrdQ=="

The result may contain A-Z, a-z, 0-9, “-” and “_”. “=” is also used if padding is true.

Answer 6

Here is one simple code for random password with lenth 8

rand_password=('0'..'z').to_a.shuffle.first(8).join

Hope it will help.