Ruby: Convert time to seconds?

Question

How can I convert a time like 10:30 to seconds? Is there some sort of built in Ruby function to handle that?

Basically trying to figure out the number of seconds from midnight (00:00) to a specific time in the day (such as 10:30, or 18:45).

Answer 1

You can use DateTime#parse to turn a string into a DateTime object, and then multiply the hour by 3600 and the minute by 60 to get the number of seconds:

require 'date'

# DateTime.parse throws ArgumentError if it can't parse the string
if dt = DateTime.parse("10:30") rescue false 
  seconds = dt.hour * 3600 + dt.min * 60 #=> 37800
end

As jleedev pointed out in the comments, you could also use Time#seconds_since_midnight if you have ActiveSupport:

require 'active_support'
Time.parse("10:30").seconds_since_midnight #=> 37800.0

Answer 2

The built in time library extends the Time class to parse strings, so you could use that. They're ultimately represented as seconds since the UNIX epoch, so converting to integers and subtracting should get you what you want.

require 'time'
m = Time.parse('00:00')
t = Time.parse('10:30')

(t.to_i - m.to_i)
=> 37800

There's also some sugar in ActiveSupport to handle these types of things.

Answer 3

I like these answers very much, especially Teddy's for its tidyness.

There's one thing to note. Teddy's answer gives second of day in current region and I haven't been able to convert Date.today.to_time to UTC. I ended up with this workaround:

Time.now.to_i % 86400

It's based on the fact that Time.now.to_i gives seconds since Unix Epoch which is always 1970-01-01T00:00:00Z, regardless of your current time zone. And the fact that there's 86400 seconds in a day as well. So this solution will always give you seconds since last UTC midnight.

Answer 4

Yet another implementation:

Time.now.to_i - Date.today.to_time.to_i # seconds since midnight

Answer 5

Perhaps there is a more succinct way, but:

t = Time.parse("18:35")
s = t.hour * 60 * 60 + t.min * 60 + t.sec

would do the trick.

Answer 6

You can simply use

Time.parse("10:30").seconds_since_midnight