How to format a string with floats in Ruby using #{variable}?
RubyRuby Problem Overview
I would like to format a string containing float variables including them with a fixed amount of decimals, and I would like to do it with this kind of formatting syntax:
amount = Math::PI
puts "Current amount: #{amount}"
and I would like to obtain Current amount: 3.14.
I know I can do it with
amount = Math::PI
puts "Current amount %.2f" % [amount]
but I am asking if it is possible to do it in the #{} way.
Ruby Solutions
Solution 1 - Ruby
You can use "#{'%.2f' % var}":
irb(main):048:0> num = 3.1415
=> 3.1415
irb(main):049:0> "Pi is: #{'%.2f' % num}"
=> "Pi is: 3.14"
Solution 2 - Ruby
Use round:
"Current amount: #{amount.round(2)}"
Solution 3 - Ruby
You can do this, but I prefer the String#% version:
puts "Current amount: #{format("%.2f", amount)}"
As @Bjoernsen pointed out, round is the most straightforward approach and it also works with standard Ruby (1.9), not only Rails:
http://www.ruby-doc.org/core-1.9.3/Float.html#method-i-round
Solution 4 - Ruby
Yes, it's possible:
puts "Current amount: #{sprintf('%.2f', amount)}"