Reputation: 8709
I'm dealing with currencies and I want to round down the number to 2 decimal places. Even if the number is 500.0, I would like it to be 500.00 to be consistent. When I do "500.00".to_d it converts it to 500.0.
Whats a good way of changing this behavior? I also use this method to round down to 2 digits and make sure it always has 2 decimals.
def self.round_down(x, n=2)
s = x.to_s
l = s.index('.') ? s.index('.') + 1 + n : s.length
s = s[0, l]
s = s.index('.') ? s.length - (s.index('.') + 1) == 1 ? s << '0' : s : s << '.00'
s.to_f
end
Upvotes: 70
Views: 98209
Reputation: 1815
There was a requirement to round DOWN.
Most other answers round 500.016 UP to 500.02
Try:
def self.round_down(x, n = 2)
"%.#{n}f" % x.to_d.truncate(n)
end
irb(main):024:0> x=500.0; '%.2f' % x.to_d.truncate(2)
=> "500.00"
irb(main):025:0> x=500.016; '%.2f' % x.to_d.truncate(2)
=> "500.01"
Upvotes: 3
Reputation: 114268
Since you are using Rails and this seems to be related to a view, there's number_with_precision
:
number_with_precision(500, precision: 2)
#=> "500.00"
I18n.locale = :de
number_with_precision(500, precision: 2)
#=> "500,00"
For currencies I'd suggest number_to_currency
:
number_to_currency(500)
#=> "$500.00"
Upvotes: 72
Reputation: 29599
In addition to mcfinnigan's answer, you can also use the following to get 2 decimal places
'%.2f' % 500 # "500.00"
This use case is known as the string format operator
Upvotes: 130
Reputation: 14881
Do not use floating point numbers to represent money. See this question for a good overview of why this is a bad idea.
Instead, store monetary values as integers (representing cents), or have a look at the money gem that provides lots of useful functionality for dealing with such values.
Upvotes: 13
Reputation: 11638
Here's a hint. 500.00 is a representation of the number 500.0
Specifically, sprintf will help you:
irb(main):004:0> sprintf "%.2f", 500.0
=> "500.00"
Upvotes: 38