From: seebs@... (Peter Seebach)
Date: 2007-06-30T11:41:54+09:00
Subject: Re: Regular Expression question

In message <0df4a451b19810ff6e06f11725324591@ruby-forum.com>, Al Cholic writes:
>Im working with regular expressions and I cant quite understand how the
>"13" is extracted from the string.
>Here is the irb output:
>irb(main):005:0> "(13)"[1..-2].to_i
>=> 13
>I dont understadn how the [1..-2] parameter removes the parenthases from
>the string.

"(13)"[0] = "("
"(13)"[1] = "1"
"(13)"[2] = "3"
"(13)"[3] = ")"

"(13)"[-1] = ")"
"(13)"[-2] = "3"
"(13)"[-3] = "1"
"(13)"[-4] = "("

"-N" counts from the end, starting with -1.

-2 is the character just before the end (the 3).  1 is the character just after
the beginning (the 1).

From "just after the beginning" to "just before the end" is the string without
the parentheses.

However, I must correct you:  You are not working with regular expressions.
There are no regular expressions here, only array slices.

-s