From: Carlos <angus@...>
Date: 2005-03-21T20:28:39+09:00
Subject: Re: string.tr and \

[Tom Counsell <tamc2@cam.ac.uk>, 2005-03-21 11.43 CET]
> Hello
> 
> I'm a little confused and would appreciate your help.  I would like to 
> remove any \ characters from a string as well as some other characters.
> 
> 'b\\c['.tr('\\','') # => 'bc', which is great.
> 
> 'b\\c'.tr('\\c','.') # => 'b\\' which is not great.
> 
> Why does adding extra characters to the tr function stop the removal of 
> \ characters?

There are two levels of escaping involved here:

First, in the literal string, you use a \ to escape the \. The method
receives the string \c.

But the method also uses \ to escape (the "^" and the "-":
  "555-7819".tr("1\\-9", "") => "55578").

So you must escape the \ with another \. In your string literal you must
write four \'s.

'b\\c'.tr('\\\\c','.')  => "b.."

Hope this helps.