prime numbers and swapping things in arrays

index.rb

def swap_first_items(arr)
  copy = arr[0..arr.length]
  i = 0
  while i < arr.size - 1
    if arr[i] > arr[i + 1]
      arr[i] = copy[i + 1]
      arr[i + 1] = copy[i]
      break
    end 
    i += 1
  end
  return arr
end 

# p swap_first_items([5, 22, 29, 39, 19, 51, 78, 96, 84])

def generate_first_100_prime_numbers 
  num = 1
  primes = []
  100.times do 
    divisor = 2
    num.times do
      if num == divisor
        primes << num
      end 
      if num % divisor == 0
        break
      end
      divisor += 1
    end 
    num += 1
  end
  return primes
end 

# p generate_first_100_prime_numbers