From: mark sparshatt <msparshatt@...>
Date: 2005-04-19T02:16:37+09:00
Subject: Re: String.sub strangeness

Belorion wrote:
> Forgive me if my Monday fog is preventing me from seeing the simple
> answer to this simple problem...
> 
> irb-enhanced(main):001:0> str = "123&456"
> => "123&456"
> irb-enhanced(main):002:0> str.sub( /\&/, "\\&" )
> => "123&456"
> irb-enhanced(main):003:0> str.sub( /\&/, "\\!" )
> => "123\\!456"
> 
> 
This is because when the string is created \\& is converted into \&. In 
a substitution string \& refers to the part of the origional string 
which matches the regexp.

> Why am I not able to escape the & in the string with an a \ ?  If I do this:
> 
> irb-enhanced(main):004:0> str.sub( /\&/, "\\\\&" )
> => "123\\&456"
> 
Another way that works is to use the block form

str.sub!( /\&/) {"\\&"}

HTH

--
Mark Sparshatt