How can I convert a BigDecimal to a 2-decimal-place string?

Question

I want to convert a BigDecimal object to a currency value to two decimal places. I don't want any rounding. How can I do it?

None of the following approaches worked:

v = BigDecimal("7.1762") w = BigDecimal("4.2")  v.to_s('2F')            # => "7.17 62" v.to_s('F')             # => "7.1762" v.to_s('%0.2F')         # => "0.71762E1" v.to_s('%0.2f')         # => "0.71762E1" v.truncate(2).to_s('F') # => "7.17" # This one looks like it worked w.truncate(2).to_s('F') # => "4.2"  # But it doesn't pad with the trailing zero(es) 

Answer 1

How about combining BigDecimal#truncate and String#%? :

"%.2f" % BigDecimal("7.1762").truncate(2) # => "7.17" "%.2f" % BigDecimal("4.2").truncate(2) # => "4.20"