Ruby日期和时间
Time类代表在Ruby中的日期和时间。在系统日期和时间由操作系统提供的功能。这个类来表示日期在1970年之前或2038年以后，这个类在系统上可能无法使用。
本在线教程将熟悉所有最想要的日期和时间的概念。
获取当前日期和时间:
以下是一个简单的例子，以获得当前的日期和时间：
#!/usr/bin/ruby -w time1 = Time.new puts "Current Time : " + time1.inspect # Time.now is a synonym: time2 = Time.now puts "Current Time : " + time2.inspect
这将产生以下结果：
Current Time : Mon Jun 02 12:02:39 -0700 2008 Current Time : Mon Jun 02 12:02:39 -0700 2008
获取组件的日期和时间：
我们可以用 Time 对象来获取日期和时间的各个组成部分。下面的例子显示相同的：
#!/usr/bin/ruby -w time = Time.new # Components of a Time puts "Current Time : " + time.inspect puts time.year # => Year of the date puts time.month # => Month of the date (1 to 12) puts time.day # => Day of the date (1 to 31 ) puts time.wday # => 0: Day of week: 0 is Sunday puts time.yday # => 365: Day of year puts time.hour # => 23: 24-hour clock puts time.min # => 59 puts time.sec # => 59 puts time.usec # => 999999: microseconds puts time.zone # => "UTC": timezone name
这将产生以下结果：
Current Time : Mon Jun 02 12:03:08 -0700 2008 2008 6 2 1 154 12 3 8 247476 UTC
Time.utc，Time.gm和Time.local函数：
可用于这两个函数以标准格式来格式化日期如下：
# July 8, 2008 Time.local(2008, 7, 8) # July 8, 2008, 09:10am, local time Time.local(2008, 7, 8, 9, 10) # July 8, 2008, 09:10 UTC Time.utc(2008, 7, 8, 9, 10) # July 8, 2008, 09:10:11 GMT (same as UTC) Time.gm(2008, 7, 8, 9, 10, 11)
下面的例子，在一个数组来获取所有组件按以下格式：
[sec,min,hour,day,month,year,wday,yday,isdst,zone]
尝试以下操作：
#!/usr/bin/ruby -w time = Time.new values = time.to_a p values
这将产生以下结果：
[26, 10, 12, 2, 6, 2008, 1, 154, false, "MST"]
这个数组可以传递给Time.utc或Time.local函数得到不同的日期格式如下：
#!/usr/bin/ruby -w time = Time.new values = time.to_a puts Time.utc(*values)
这将产生以下结果：
Mon Jun 02 12:15:36 UTC 2008
跟随着的方式来获得内部表示（依赖于平台）历元以来的秒数时间：
# Returns number of seconds since epoch time = Time.now.to_i # Convert number of seconds into Time object. Time.at(time) # Returns second since epoch which includes microseconds time = Time.now.to_f
时区和夏令时：
可以使用一个 Time 对象来获取相关的所有信息的时区和夏令如下：
time = Time.new # Here is the interpretation time.zone # => "UTC": return the timezone time.utc_offset # => 0: UTC is 0 seconds offset from UTC time.zone # => "PST" (or whatever your timezone is) time.isdst # => false: If UTC does not have DST. time.utc? # => true: if t is in UTC time zone time.localtime # Convert to local timezone. time.gmtime # Convert back to UTC. time.getlocal # Return a new Time object in local zone time.getutc # Return a new Time object in UTC
格式化时间和日期：
有各种各样的方式来格式化日期和时间。下面是一个例子，说明几个：
#!/usr/bin/ruby -w time = Time.new puts time.to_s puts time.ctime puts time.localtime puts time.strftime("%Y-%m-%d %H:%M:%S")
这将产生以下结果：
Mon Jun 02 12:35:19 -0700 2008 Mon Jun 2 12:35:19 2008 Mon Jun 02 12:35:19 -0700 2008 2008-06-02 12:35:19
时间格式化指令：
使用下表中的这些指令的方法 Time.strftime.
| Directive | Description |
|---|---|
| %a | The abbreviated weekday name (Sun). |
| %A | The full weekday name (Sunday). |
| %b | The abbreviated month name (Jan). |
| %B | The full month name (January). |
| %c | The preferred local date and time representation. |
| %d | Day of the month (01 to 31). |
| %H | Hour of the day, 24-hour clock (00 to 23). |
| %I | Hour of the day, 12-hour clock (01 to 12). |
| %j | Day of the year (001 to 366). |
| %m | Month of the year (01 to 12). |
| %M | Minute of the hour (00 to 59). |
| %p | Meridian indicator (AM or PM). |
| %S | Second of the minute (00 to 60). |
| %U | Week number of the current year, starting with the first Sunday as the first day of the first week (00 to 53). |
| %W | Week number of the current year, starting with the first Monday as the first day of the first week (00 to 53). |
| %w | Day of the week (Sunday is 0, 0 to 6). |
| %x | Preferred representation for the date alone, no time. |
| %X | Preferred representation for the time alone, no date. |
| %y | Year without a century (00 to 99). |
| %Y | Year with century. |
| %Z | Time zone name. |
| %% | Literal % character. |
时间算术：
可以在时间上做简单的算术如下：
now = Time.now # Current time puts now past = now - 10 # 10 seconds ago. Time - number => Time puts past future = now + 10 # 10 seconds from now Time + number => Time puts future diff = future - now # => 10 Time - Time => number of seconds puts diff
这将产生以下结果：
Thu Aug 01 20:57:05 -0700 2013 Thu Aug 01 20:56:55 -0700 2013 Thu Aug 01 20:57:15 -0700 2013 10.0
