From: ricpelo@...
Date: 2005-10-26T04:52:02+09:00
Subject: Weird thing with "sub" and "rjust"

I would like to write code which does the following transformations:

  "hello-3.jpg"   => "hello-003.jpg"
  "hello-42.jpg"  => "hello-042.jpg"
  "hello-250.jpg" => "hello-250.jpg"

And I tried this:

  string.sub(/(\d+)/, '\1'.rjust(3, '0'))

where "string" is one of the above strings (in the left side of =>).

It works with:

  'hello-42.jpg'.sub(/(\d+)/, '\1'.rjust(3, '0'))
  => "hello-042.jpg"

But it doesn't works with:

  'hello-3.jpg'.sub(/(\d+)/, '\1'.rjust(3, '0'))
  => "hello-03.jpg"

And doesn't works with:

  'hello-250.jpg'.sub(/(\d+)/, '\1'.rjust(3, '0'))
  => "hello-0250.jpg"

What's wrong?

Thanks a lot.