查找给定周数的日期 [英] Finding the date for a given week number

问题描述

我正在根据给定年份的周数来做一些日期数学。例如：

  date = Date.today＃2012年3月5日，星期一
 puts date.cwyear＃2012 
 put date.cweek＃10（2012年第10周）
  

现在我知道本周是，我想知道下周和上周是什么。我需要年（2012）和周数（10），并将其重新转换成日期对象，以便我可以计算下一个/上一周的值。我该怎么做？

解决方案

你想要 Date.commercial ：

  require'date'
 now = Date.today＃=> 2012-03-05 
 monday_next_week = Date.commercial（now.cwyear，now.cweek + 1）＃=> 2012-03-12 
 next_sunday_or_today = monday_next_week  -  1＃=>请注意，星期一星期几开始，所以如果你是星期天的，请问下一个星期一 - 你会得到同一天。
 
 
 
另请注意，如果您不想要星期一，您还可以在方法中指定日期号码： / p> 
 
 
  thursday_next_week = Date.commercial（now.cwyear，now.cweek + 1,4）＃=> 2012-03-15 
  
 
I am trying to do some date math based on the week number of a given year. For example:
date = Date.today # Monday, March 5, 2012
puts date.cwyear  # 2012
puts date.cweek   # 10 (10th week of 2012)
Now that I know what the current week is, I want to figure out what the next week and previous week are. I need to take the year (2012) and the week number (10) and turn it back into a date object so I can calculate the value for the next/previous week. How can I do this?
解决方案
You want Date.commercial:
require 'date'
now = Date.today                                           #=> 2012-03-05
monday_next_week = Date.commercial(now.cwyear,now.cweek+1) #=> 2012-03-12
next_sunday_or_today = monday_next_week - 1                #=> 2012-03-11
Note that weeks start on Monday, so if you are on a Sunday and ask for next monday - 1 you'll get the same day.

Note also that if you don't want Mondays you can also specify the day number in the method:
thursday_next_week = Date.commercial(now.cwyear,now.cweek+1,4) #=> 2012-03-15


                        
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