From: Pete Yandell <pete@...>
Date: 2007-07-20T13:57:18+09:00
Subject: Re: Is there a replacement for sub?

Michael W. Ryder wrote:
> I was trying to come up with a way to remove x instances of a character 
> from a string and came up with a problem.  If I enter:
> 
> a = "a b c d e f"
> for i in 1..3
>   a = a.sub!(' ', '')
> end
> puts a  ==> returns 'abcd e f' which is correct.
> 
> But if I enter:
> 
> a = "a b c d e f"
> for i in 1..10
>   a = a.sub!(' ', '')
> end
> puts a  ==> returns error.rb:3: private method `sub!' called for 
> nil:NilClass (NoMethodError, and a is now nil.

a.sub! returns nil if no matches are found. You want either:

   a = a.sub(' ', '')

or

   a.sub!(' ', '')

And try using times rather than a for loop and a useless variable:

   3.times { a.sub!(' ', '') }

You could also replace the whole thing with:

   "a b c d e f".split(' ', 4).join

Pete Yandell
http://notahat.com/