Re: Easy regexp issue

[Barry Margolin <barmar@alum.mit.edu>]

In article <mailman.3295.1169191738.2155.help-gnu-emacs@gnu.org>,
 Kevin Rodgers <kevin.d.rodgers@gmail.com> wrote:

> HS wrote:
> > I'm finding this quite odd:
> > I want to replace all slashes for backslashes in a string, but i'm
> > having trouble!
> > 
> > Running this:
> > (replace-regexp-in-string "/" "\\" "c:/emacs/lisp/")
> > I get:
> > Debugger entered--Lisp error: (error "Invalid use of `\\' in
> > replacement text")
> > 
> > And if I try:
> > (replace-regexp-in-string "/" "\" "c:/emacs/lisp/")
> > I get:
> > Debugger entered--Lisp error: (scan-error "Unbalanced parentheses" 302
> > 1)
> > 
> > So, I don't see any other options!
> > I know the problems is there because I replace for another string then
> > it works:
> > (replace-regexp-in-string "/" "x" "c:/emacs/lisp/")
> > "c:xemacsxlispx"
> 
> See the LITERAL argument in the doc string for replace-regexp-in-string:
> 
> (replace-regexp-in-string "/" "\\" "c:/emacs/lisp/" nil t)

Or

(replace-regexp-in-string "/" "\\\\" "c:/emacs/lisp/")

This is necessary because backslash is an escape character at two 
levels: Lisp strings and regexp replacement strings (e.g. the sequence 
\1 in the replacement represents a group matched in the regexp).  So the 
replacement string needs to be \\, and you need to escape each \ in the 
string.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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