Date and Time in Ruby


The Time class represents dates and times in Ruby. It is a thin layer over the system date and time functionality provided by the operating system. This class may be unable on your system to represent dates before 1970 or after 2038.

This tutorial will make you familiar with all the most wanted concepts of date and time.

Getting Current Date and Time:

Following is the simple example to get current date and time:

      #!/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
      

This will produce following result:

      Current Time : Mon Jun 02 12:02:39 -0700 2008
      Current Time : Mon Jun 02 12:02:39 -0700 2008
      

 

Getting components of a Date & Time:

We can use Time object to get various components of date and time. Following is the example showing the same:

      #!/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
      

This will produce following result:

      Current Time : Mon Jun 02 12:03:08 -0700 2008
      2008
      6
      2
      1
      154
      12
      3
      8
      247476
      UTC
      

 

Time.utc, Time.gm and Time.local Functions:

These two functions can be used to format date in standard format as follows:

      # 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)
      

Following is the example to get all components in an array in the following format:

      [sec,min,hour,day,month,year,wday,yday,isdst,zone]
      

Try the following:

      #!/usr/bin/ruby -w
      
      time = Time.new
      
      values = t.to_a
      p values
      

This will generate following result:

      [26, 10, 12, 2, 6, 2008, 1, 154, false, "MST"]
      

This array could be passed to Time.utc or Time.local functions to get different format of dates as follows:

      #!/usr/bin/ruby -w
      
      time = Time.new
      
      values = t.to_a
      puts Time.utc(*values)
      

This will generate following result:

      Mon Jun 02 12:15:36 UTC 2008
      

Followin is the way to get time represented internally as seconds since the (platform-dependent) epoch:

      # 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
      

 

Timezones and daylight savings time:

You can use a Time object to get all the information related to Timezones and daylight savings as follows:

      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
      

 

Formatting Times and Dates:

There are various ways to format date and time. Here is one example showing few:

      #!/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")
      

This will produce following result:

      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
      

 

Time Formatting Directives:

These directives in the following table are used with the method Time.strftime.

Directive Description
%aThe abbreviated weekday name (Sun).
%AThe full weekday name (Sunday).
%bThe abbreviated month name (Jan).
%BThe full month name (January).
%cThe preferred local date and time representation.
%dDay of the month (01 to 31).
%HHour of the day, 24-hour clock (00 to 23).
%IHour of the day, 12-hour clock (01 to 12).
%jDay of the year (001 to 366).
%mMonth of the year (01 to 12).
%MMinute of the hour (00 to 59).
%pMeridian indicator (AM or PM).
%SSecond of the minute (00 to 60).
%UWeek number of the current year, starting with the first Sunday as the first day of the first week (00 to 53).
%WWeek number of the current year, starting with the first Monday as the first day of the first week (00 to 53).
%wDay of the week (Sunday is 0, 0 to 6).
%xPreferred representation for the date alone, no time.
%XPreferred representation for the time alone, no date.
%yYear without a century (00 to 99).
%YYear with century.
%ZTime zone name.
%%Literal % character.

 

Time arithmetic:

You can do simple arithmetic with time as follows:

      now = Time.now     # Current time
      past = now - 10    # 10 seconds ago. Time - number => Time
      future = now + 10  # 10 seconds from now Time + number => Time
      future - now       # => 10  Time - Time => number of seconds