Question

I found out Prime.new in the mathn library in Ruby. I was using it to generate primes for a problem. I want to iterate over all primes between 1 and 1000 using Primes.new. Is there any way to use Prime.new in a for loop or iterate over primes in some way?

Answer 1

You can also get the n first prime numbers like that :

Prime.each(100) do |prime|
  p prime  #=> 2, 3, 5, 7, 11, ...., 97
end

cf : http://www.ruby-doc.org/gems/docs/b/backports-2.6.1/Prime.html

EDIT : to get the n first prime numbers with above a given value, I would so something like that (this is a draft)

require 'mathn'

def prime_numbers_from start, n
  primes = []
  Prime.each(n) do |prime|
    primes << prime if prime > start
  end
  primes
end

prime_numbers_from(10, 30)
# returns => [11, 13, 17, 19, 23, 29]