From: MonkeeSage <MonkeeSage@...>
Date: 2006-09-16T08:20:55+09:00
Subject: Re: No regex backreference with four backslashes


gabriel.birke@gmail.com wrote:
> I expected that when I remove the space from the first expression, that
> my characters would get quoted. instead, the four backslashes get
> interpreted as two escaped backslashes and the 1 as a literal
> character. Can somebdoy shed some light on the how and why of this
> case? Especially, why the solution with the five backslashes doesn't
> yield double backlashes in the result string?

In the replacement string, a backreference is a backslash followed by a
number -- reference(\1) -- but a double-backslash is treated as a
literal single backslash, so \\1 == literal(\1). So then, three
backslashes and a number, \\\1 is equal to literal(\) reference(\1).
Four means literal(\\1). Finally, five means literal(\\) reference(\1),
and thus, since backslashes must be escaped to be seen as a single
backslash in a string, you end up with the resulting string
"1\\23\\45", meaning 1\23\45. Hope that makes sense.

Regards,
Jordan