What's the doc of replace-regexp-in-string saying ?

[bolega]

Hello All,

In this doc, its not clear what the role of \' is ?

Can any kind soul give various examples of usage of this to match and
replace regexp with a given STRING , I repeat, in a STRING, not the
buffer.

Bolega



replace-regexp-in-string is a compiled Lisp function in `subr'.
(replace-regexp-in-string REGEXP REP STRING &optional FIXEDCASE
LITERAL SUBEXP START)

Replace all matches for REGEXP with REP in STRING.

Return a new string containing the replacements.

Optional arguments FIXEDCASE, LITERAL and SUBEXP are like the
arguments with the same names of function `replace-match'.  If START
is non-nil, start replacements at that index in STRING.

REP is either a string used as the NEWTEXT arg of `replace-match' or a
function.  If it is a function it is applied to each match to generate
the replacement passed to `replace-match'; the match-data at this
point are such that match 0 is the function's argument.

To replace only the first match (if any), make REGEXP match up to \'
and replace a sub-expression, e.g.
  (replace-regexp-in-string "\(foo\).*\'" "bar" " foo foo" nil nil 1)
    => " bar foo"