Ruby日期和時間
Time類代表在Ruby中的日期和時間。在係統日期和時間由操作係統提供的功能。這個類來表示日期在1970年之前或2038年以後，這個類在係統上可能無法使用。
本教學將熟悉所有最想要的日期和時間的概念。
獲取當前日期和時間:
以下是一個簡單的例子，以獲得當前的日期和時間：
#!/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
這將產生以下結果：
Current Time : Mon Jun 02 12:02:39 -0700 2008 Current Time : Mon Jun 02 12:02:39 -0700 2008
獲取組件的日期和時間：
我們可以用 Time 對象來獲取日期和時間的各個組成部分。下麵的例子顯示相同的：
#!/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
這將產生以下結果：
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函數：
可用於這兩個函數以標準格式來格式化日期如下：
# 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)
下麵的例子，在一個數組來獲取所有組件按以下格式：
[sec,min,hour,day,month,year,wday,yday,isdst,zone]
嘗試以下操作：
#!/usr/bin/ruby -w time = Time.new values = time.to_a p values
這將產生以下結果：
[26, 10, 12, 2, 6, 2008, 1, 154, false, "MST"]
這個數組可以傳遞給Time.utc或Time.local函數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)
這將產生以下結果：
Mon Jun 02 12:15:36 UTC 2008
跟隨著的方式來獲得內部表示（依賴於平台）曆元以來的秒數時間：
# 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
時區和夏令時：
可以使用一個 Time 對象來獲取相關的所有信息的時區和夏令如下：
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
格式化時間和日期：
有各種各樣的方式來格式化日期和時間。下麵是一個例子，說明幾個：
#!/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")
這將產生以下結果：
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
時間格式化指令：
使用下表中的這些指令的方法 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. |
時間算術：
可以在時間上做簡單的算術如下：
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
這將產生以下結果：
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
