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rubybignum

Way to count number of digits in a Bignum

I am writing a ruby method as follows: 

def build_array(word)
  word_copy = word
  array = []
  length = word_copy.length
  for i in 1..length do
    array[i] = word_copy % 10
    word_copy = word_copy/10;
  end
 puts array
end

I would like to create an iterator which counts from 1 to the number of digits in a Bignum.

Bignum.length is not valid ruby. Alternatively, is there a way to bust up a Bignum into an array of its constituent digits (Which is what I am trying to implement).

Thanks!

Solution

  • You could convert it to String and count its size

    b = 2_999_999_000_000_000
p b.class
#=> Bignum
p b.to_s.size
#=> 16
p b.to_s.split("").map(&:to_i)
#=> [2, 9, 9, 9, 9, 9, 9, 0, 0, 0, 0, 0, 0, 0, 0, 0]