From: William James <w_a_x_man@...>
Date: 2007-05-04T12:05:05+09:00
Subject: Re: Is there a better way to do this?

On May 3, 9:03 pm, "Michael W. Ryder" <_mwry...@worldnet.att.net>
wrote:
> Dan Zwell wrote:
> >> I am trying to come up with a "generic" formatting routine so that I
> >> could feed it something like sform("123456789", "000-00-0000") or
> >> sform("1234567890", "(000) 000-0000") or sform("123456", "00/00/00")
> >> and it would work.  I could easily do something like you suggest, and
> >> for some cases it might be better, but I want something I can for any
> >> number of formats.  Thanks for the input.
>
> > welcome.
>
> > require 'enumerator'
>
> > def sform(num, fmt)
> >   # convert num to array (of one digit strings):
> >   num = num.to_enum(:each_byte).map { |code| code.chr }
>
> >   # for each zero, replace it with a digit popped off the
> >   # front of the array of numbers (or characters):
> >   fmt.gsub(/0/) { num.shift }
> > end
>
> > dan
>
> Your method is much better than my C style one.  With a little work to
> handle exceptions it should generally work.  The only problem I have
> found so far is that it doesn't handle periods in the number string
> properly -- i.e. sform("12345.67", "$00,000.00") returns $12,345..6"
> instead of $12,345.67".  Something for me to work on.  Thanks for the code.

I made some changes to handle the decimal point
and the case when there are fewer digits in the
string than in the format.

# The part on the left of the decimal point.
def sform_left( str, fmt )
  result = ''
  fmt = fmt.split(//)
  str.split(//).reverse_each{|d|
    while fmt.last != '0' do
      result = fmt.pop + result
    end
    fmt.pop
    result = d + result
  }
  result = fmt.first + result  if fmt.first != '0'
  result
end

# The part on the right of the decimal point.
def sform_right( str, fmt )
  ary = str.split(//)
  fmt.gsub( /0/ ){ ary.shift || '0' }
end

def sform( str, fmt )
  str = str.split('.')
  fmt = fmt.split('.')
  result = sform_left( str[0], fmt[0])
  if fmt[1]
    result += "." + sform_right( str.last, fmt.last)
  end
  result
end

puts sform("12345", "$00,000")
puts sform("1234", "$00,000")
puts sform("123", "$00,000")
puts sform("12345.6", "$00,000.00")
puts sform("12345.678", "$00,000.00")
puts sform("12345.678", "$00,000")

--- output ---
$12,345
$1,234
$123
$12,345.60
$12,345.67
$12,345