From: Phrogz <gavin@...>
Date: 2006-11-26T01:55:07+09:00
Subject: Re: Formating Floats as Money

John Kopanas wrote:
> I have a number that is of type float.  I want to format it as dollars
> and cents.  How do you recommend I do it? :-)

Here's my shot at it:

class Numeric
  def to_currency( pre_symbol='$', thousands=',', decimal='.',
post_symbol=nil )
    "#{pre_symbol}#{
      ( "%.2f" % self ).gsub(
        /(\d)(?=(?:\d{3})+(?:$|\.))/,
        "\\1#{thousands}"
      )
    }#{post_symbol}"
  end
end

[
1,21,321,4321,54321,654321,7654321,87654321,
1.5,21.5,321.5,4321.5,54321.5,654321.5,
].each{ |n|
  puts "%14s -> %s" % [ n.to_s, n.to_currency ]
  puts "%14s -> %s" % [ (-n).to_s, (-n).to_currency ]
}

#=>             1 -> $1.00
#=>            -1 -> $-1.00
#=>            21 -> $21.00
#=>           -21 -> $-21.00
#=>           321 -> $321.00
#=>          -321 -> $-321.00
#=>          4321 -> $4,321.00
#=>         -4321 -> $-4,321.00
#=>         54321 -> $54,321.00
#=>        -54321 -> $-54,321.00
#=>        654321 -> $654,321.00
#=>       -654321 -> $-654,321.00
#=>       7654321 -> $7,654,321.00
#=>      -7654321 -> $-7,654,321.00
#=>      87654321 -> $87,654,321.00
#=>     -87654321 -> $-87,654,321.00
#=>           1.5 -> $1.50
#=>          -1.5 -> $-1.50
#=>          21.5 -> $21.50
#=>         -21.5 -> $-21.50
#=>         321.5 -> $321.50
#=>        -321.5 -> $-321.50
#=>        4321.5 -> $4,321.50
#=>       -4321.5 -> $-4,321.50
#=>       54321.5 -> $54,321.50
#=>      -54321.5 -> $-54,321.50
#=>      654321.5 -> $654,321.50
#=>     -654321.5 -> $-654,321.50