Subtract n hours from a DateTime in Ruby

Question

I have a Ruby DateTime which gets filled from a form. Additionally I have n hours from the form as well. I\'d like to subtract those n hours from the previous DateTime. (To

Answer 1

You didn't say what use you need to make of the value you get, but what about just dividing your hours by 24 so you're subtracting a fraction of a day?

mydatetime = DateTime.parse(formvalue)
nhoursbefore = mydatetime - n / 24.0