From volkmar.klatt at bnv-bamberg.de  Mon Apr  7 23:10:04 2008
From: volkmar.klatt at bnv-bamberg.de (volkmar.klatt at bnv-bamberg.de)
Date: Mon,  7 Apr 2008 23:10:04 +0200 (CEST)
Subject: [Rd] "\0" gives no warning "unknown escape sequence" (PR#11107)
Message-ID: <20080407211005.00AA8282EFF7@mail.pubhealth.ku.dk>

Full_Name: Volkmar Klatt
Version: 2.6.2
OS: linux
Submission from: (NULL) (84.147.0.178)


Hello,

the documentation article
?Quotes 
from package:base could be improved by discussing
the meaning of "\0" escape sequence.
In R (currently used: R-2.6.2), a "\0" in a string will
silently terminate that string, just as it would in C code.
There is no warning about an unknown escape sequence.
(cf. R FAQ 7.37)

# example:
s <- "abc\0def"
s
# --> [1] "abc"
nchar(s) 
# --> [1] 3

The "\0" seems to be so fundamental, that it cannot be handled by
any R function, am I right?
E.g., the function escapeBS (package:Hmisc) does not correctly
handle "\0" sequences, that is in contrast to what is stated in its 
article ?escapeBS :
"'escapeBS' will escape any backslash '\backslash' in a string.

# example:
library(Hmisc)
escapeBS("abc\0def")
# -->[1] "abc"

Bye,
Volkmar Klatt
volkmar.klatt AT bnv-bamberg.de



[Rd] "\0" gives no warning "unknown escape sequence" (PR#11107)
volkmar.klatt at bnv-bamberg.de