From: Sylvester Keil <sylvester.keil@...>
Date: 2011-11-22T07:30:44+09:00
Subject: Re: Regular expression match


On Nov 21, 2011, at 11:02 PM, rubix Rubix wrote:

> Hi,
> 
> Can anyone explain to me this regular expression, please:
> str[/\A([a-z]\w*)/, 1]

Check out the documentation:

ri String#[]

When given a regular expression and a fixnum, you're matching the string against the regular expression and returning the capturing group indicated by the fixnum. That is to say, your example will match a word beginning with a lower case letter at the beginning of the string. Since \A is an anchor and therefore not part of the matched string and if I am not mistaken, your expression is actually equivalent to just

str[/\A[a-z]\w*/]

If there is a particular reason for using the capturing group over the entire expression there you should probably add a comment to document it!

Sylvester