Time calculate method in rails

Dear all

Is there any existing function in rails to calculate time? I have google
it but no information found..

For example
a = "2009-07-16 12:34".to_time
b = "2009-07-16 12:04".to_time
some_method(a,b) return "30 mins ago"

c = "2009-07-16 12:34".to_time
d = "2009-07-12 09:09".to_time
some_method(c,d) return "4 days ago"

If not, I will write it by my own. But it can save my time if there is
existing method to do so...

Have a look at the documentation for the Time class. You can just
subtract the times.

a = "2009-07-16 12:34".to_time

=> Thu Jul 16 12:34:00 UTC 2009

b = "2009-07-16 12:04".to_time

=> Thu Jul 16 12:04:00 UTC 2009

diff = a-b

=> 1800.0 # 30 mins in seconds

Colin