How to generate a random string in Ruby

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?

To make your first into one statement:

(0...8).collect { |n| value << (65 + rand(25)).chr }.join()

I don't know ruby, so I can't give you the exact syntax, but I would set a constant string with the list of acceptable characters, then use the substring operator to pick a random character out of it.

The advantage here is that if the string is supposed to be user-enterable, then you can exclude easily confused characters like l and 1 and i, 0 and O, 5 and S, etc.

This is almost as ugly but perhaps as step in right direction?

(1..8).map{|i| ('a'..'z').to_a[rand(26)]}.join

require 'sha1'
srand
seed = "--#{rand(10000)}--#{Time.now}--"
Digest::SHA1.hexdigest(seed)[0,8]

We've been using this on our code:

class String

def self.random(length=10)
('a'..'z').sort_by {rand}[0,length].join
end

end

The maximum length supported is 25 (we're only using it with the default anyway, so hasn't been a problem).

Someone mentioned that 'a'..'z' is suboptimal if you want to completely avoid generating offensive words. One of the ideas we had was removing vowels, but you still end up with WTFBBQ etc.

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

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

In ruby 1.9 one can use Array's choice method which returns random element from array

`pwgen 8 1`.chomp