查找周日期

以下代码将产生两个日期间的所有星期日的日期。

 

  def every_sunday(d1, d2)
    one_day = d1.is_a?(Time) ? 60 * 60 * 24 : 1
    sunday = d1 + ((7 - d1.wday) % 7) * one_day
    while sunday < d2
      yield sunday
      sunday += one_day * 7
    end
  end

  def print_every_sunday(d1, d2)
    every_sunday(d1, d2){ |sunday| puts sunday.strftime("%x") }
  end

  print_every_sunday(Time.local(2011, 2, 1), Time.local(2011, 2, 20))
  # => 02/06/11
  # => 02/13/11