From: Martin Jansson <martialis@...>
Date: 2006-06-29T02:13:21+09:00
Subject: Re: string manipulation

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"

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