birthdate.rb

require 'date'
require 'active_support/all'

# Calcucaltes the age from a provided birthdate
#
# Returns - Age as Integer
def get_age(birthdate)
  today = Date.today
  birthdate = Date.parse(birthdate)
  years = (today.year - birthdate.year)
  birthday_this_year = birthdate + years.years

  if birthday_this_year >= today
    years - 1
  else
    years
  end
end

print 'Please enter your Birthdate (dd.mm.yyyy) > '
input = gets.chomp

result = get_age(input)
puts "You are #{get_age(input)} years old"