Ruby Date & Time (Date & Time)

The Time class in Ruby is used to represent dates and times. It is based on the system date and time provided by the operating system. This class may not be able to represent dates before 1970 or after 2038.

This tutorial will familiarize you with all the important concepts of dates and times.

Creating the Current Date and Time

Below is a simple example to get the current date and time:

Example

#!/usr/bin/ruby -w
# -*- coding: UTF-8 -*-

time1 = Time.new

puts "Current Time : " + time1.inspect

# Time.now is an equivalent method
time2 = Time.now
puts "Current Time : " + time2.inspect

The above example outputs the following result:

Current Time : 2015-09-17 15:23:14 +0800
Current Time : 2015-09-17 15:23:14 +0800

Getting Date & Time Components

We can use the Time object to get various date and time components. See the following example:

Example

#!/usr/bin/ruby -w
# -*- coding: UTF-8 -*-

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 month (1 to 31)
puts time.wday    # => 0: Day of the week (0 is Sunday)
puts time.yday    # => 365: Day of the 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": Time zone name

The above example outputs the following result:

Current Time : 2015-09-17 15:24:44 +0800
2015
9
17
4
260
15
24
44
921519
CST

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

These functions can be used to format dates in standard format, as shown below:

# 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)

The following example gets all the components in an array:

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

Try the following example:

Example

#!/usr/bin/ruby -w

time = Time.new

values = time.to_a
p values

The above example outputs the following result:

[39, 25, 15, 17, 9, 2015, 4, 260, false, "CST"]

This array can be passed to Time.utc or Time.local functions to get different formats of dates, as shown below:

Example

#!/usr/bin/ruby -w

time = Time.new

values = time.to_a
puts Time.utc(*values)

The above example outputs the following result:

2015-09-17 15:26:09 UTC

Here is how to get time, in seconds since the Epoch (platform-dependent):

# Returns seconds since Epoch
time = Time.now.to_i  

# Convert number of seconds into Time object
Time.at(time)

# Returns current time, including microseconds
time = Time.now.to_f

Time Zones and Daylight Saving Time

You can use the Time object to get all information related to time zones and daylight saving time, as shown below:

time = Time.new

# Here is the interpretation
time.zone       # => "UTC": returns the timezone
time.utc_offset # => 0: UTC is 0 seconds offset from UTC
time.zone       # => "PST" (or whatever the timezone is)
time.isdst      # => false: If UTC does not have DST (Daylight Saving Time)
time.utc?       # => true: If in UTC time zone
time.localtime  # Convert to local timezone
time.gmtime     # Convert back to UTC
time.getlocal   # Returns a new Time object in local zone
time.getutc     # Returns a new Time object in UTC

Formatting Time and Date

There are various ways to format dates and times. The following example demonstrates some of them:

Example

#!/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")

The above example outputs the following result:

2015-09-17 15:26:42 +0800
Thu Sep 17 15:26:42 2015
2015-09-17 15:26:42 +0800
2015-09-17 15:26:42

Time Formatting Directives

The following directives can be used with the Time.strftime method:

Time Arithmetic

You can perform simple arithmetic with time, as shown below:

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

The above example outputs the following result:

2015-09-17 15:27:08 +0800
2015-09-17 15:26:58 +0800
2015-09-17 15:27:18 +0800
10.0