From: Florian Gross <flgr@...>
Date: 2005-03-23T06:34:53+09:00
Subject: Re: Any guides for good coding in Ruby?

Arfin wrote:

> Is there some kind of class to format numbers? Something to let you
> transform:
> 
> 1	=>	"0001"

"%04d" % 1

This is pretty much the same as sprintf() in C.

But in this case you can also do:

"1".rjust(4, "0")

> 1234	=>	"1,234.00"

I'd do that like this, even though there's other versions:

def number_format(number, padding_char = ",")
   result = number.to_s
   while pos = result.rindex(/\d{4}(?=\D|\Z)/)
     result[pos + 1, 0] = padding_char
   end
   return result
end

irb(main):001:0> number_format 100_000_000
=> "100,000,000"
irb(main):002:0> number_format 10_000_000_000
=> "10,000,000,000"
irb(main):003:0> number_format "foo 10000000000 bar 50 qux 5000"
=> "foo 10,000,000,000 bar 50 qux 5,000"