Ruby 取得指定月日期数的方法

require 'date'

day = Date.new(2008, 2, -1)
end_of_month = day.strftime('%d').to_i
year_and_month = day.strftime('%Y%m')
for today in 1..end_of_month do
p sprintf('%s%02d', year_and_month, today)
end