From: Rob Biedenharn <Rob@...>
Date: 2006-06-29T03:28:38+09:00
Subject: Re: string manipulation


On Jun 28, 2006, at 1:13 PM, Martin Jansson wrote:

> siva kumar wrote:
>> How to add "-" between the numbers
>>  Eg:
>> 123456789123456789 as 12-3456-7891-2345-6789
>
> irb(main):001:0>  s = 123456789123456789.to_s
> => "123456789123456789"
>
> irb(main):002:0> "#{s[0,2]}-#{s[2,4]}-#{s[6,4]}-#{s[10,4]}-#{s[14,4]}"
> => "12-3456-7891-2345-6789"
>
> irb(main):003:0>
> "#{s[0..1]}-#{s[2..5]}-#{s[6..9]}-#{s[10..13]}-#{s[14..17]}"
> => "12-3456-7891-2345-6789"
>
> irb(main):004:0> def f(n, p=4, s="")
> irb(main):005:1>   i= n.to_i
> irb(main):006:1>   return s if i<=0
> irb(main):007:1>   a= 10**p
> irb(main):008:1>   f(i/a, p, (i%a).to_s+(s=="" ? "" : "-"+s))
> irb(main):009:1> end
> => nil
>
> irb(main):010:0> f s
> => "12-3456-7891-2345-6789"
>
> irb(main):011:0> f s.to_i
> => "12-3456-7891-2345-6789"
>
> irb(main):012:0> f s, 5
> => "123-45678-91234-56789"

building on the ActionPack helper number_with_delimiters

def number_with_dashes(number, groups=4, delimiter="-")
   re = %r/(\d)(?=(\d{#{groups}})+(?!\d))/
   number.to_s.gsub(re, "\\1#{delimiter}")
end

irb(main):023:0> number_with_dashes(123456789123456789)
=> "12-3456-7891-2345-6789"