How to round a float value [closed]

问题

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.

Closed 7 years ago.

I'm trying to round a float value as follows:

(0.11 + 0.22 + 0.23 / 3).round(2)

Does anyone know if there is other effective way to round up?

回答1:

If you always want to round up and never down, you can do this:

(0.411 * 100).ceil / 100.0 # => 0.42

Otherwise just use round. Or use the string formatter if you don't mind your float turning into a string.

回答2:

The main ways to round a floating point number in Ruby are via the Float#round method or the String#% (format) operator. For example:

f = (0.11 + 0.22 + 0.23 / 3) # => 0.4066666666666667
f.round(2)  # =>  0.41
"%.02f" % f # => "0.41"

来源：https://stackoverflow.com/questions/13716057/how-to-round-a-float-value