Get person's age in Ruby

Question

I\'d like to get a person\'s age from its birthday. now - birthday / 365 doesn\'t work, because some years have 366 days. I came up with the following code:

Answer 1

I believe this is functionally equivalent to @philnash's answer, but IMO more easily understandable.

class BirthDate
  def initialize(birth_date)
    @birth_date = birth_date
    @now = Time.now.utc.to_date
  end

  def time_ago_in_years
    if today_is_before_birthday_in_same_year?
      age_based_on_years - 1
    else
      age_based_on_years
    end
  end

  private

  def age_based_on_years
    @now.year - @birth_date.year
  end

  def today_is_before_birthday_in_same_year?
    (@now.month < @birth_date.month) || ((@now.month == @birth_date.month) && (@now.day < @birth_date.day))
  end
end

Usage:

> BirthDate.new(Date.parse('1988-02-29')).time_ago_in_years
 => 31