From: Rick DeNatale <rick.denatale@...>
Date: 2008-04-24T22:15:33+09:00
Subject: Re: puts "\\".gsub("\\", "\\\\")

On Thu, Apr 24, 2008 at 8:35 AM, Simon Krahnke <overlord@gmx.li> wrote:
> * martinus <martin.ankerl@gmail.com> (11:53) schrieb:
>
>
>
>  > Hello, I have a mini-ruby quiz. Guess what this line of code writes to
>  > the console, then try it for yourself:
>  >
>  > puts "\\".gsub("\\", "\\\\")
>  >
>  > Why is that so?
>
>  Well, it's an faq. In short: The backslash is special in strings *and*
>  in the replacement text. So for every literal backslash you need four
>  backslashes, which is quite unreadable. If you don't need \1 and Co you
>  better use the block form: gsub("\\") { "\\\\" }.

Another thing which trips up newbies, and sometimes not so newbies, is
the difference between the contents of a sring, and the 'inspect'
presentation of a string, particularly when the string contains
escapes:

irb(main):001:0> puts "\\"
\
=> nil
irb(main):002:0> p "\\"
"\\"
=> nil

The point is that the literal string "\\" only contains one character.
 The puts method shows you the contents of the string, while p (which
is practically equivalent to puts string.inspect produces a literal
representation.

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/