From: Paul Sutton <paul@...>
Date: 2012-06-14T01:11:25+09:00
Subject: Re: Problem with reg exp

On Wed, 2012-06-13 at 13:21 +0900, Matthew Kerwin wrote:
> I'd have to think a lot harder about how you're getting what you're
> getting with str2, but I'm already pretty sure the actual question can
> be resolved using =~ or String#match

In this case:

"ABC13B2013KEYWORD".split(/([a-zA-Z]+)(.*)(KEYWORD?)/)
 => ["","ABC","12A2012","KEYWORD"]

what is happening is that split's results consist of both the strings
between the matched delimiters, and (for each match of the delimiter)
any match groups from the delimiters themselves. In this case, the regex
matches the entire string. Without match groups it would give:

"ABC13B2013KEYWORD".split(/[a-zA-Z]+.*KEYWORD?/)
 => [""]

(An empty string since the delimiter matched from the start of the
string. Logically there should be a second empty string for the match at
the end of the string, but that is suppressed unless you give the second
arg to split).

-Paul