I get similar results on an Apple Mac G5
running OS X, though nchar() works.
> raw0 <- as.raw(c(65:68, 0 , 70))
> string0 <- rawToChar(raw0)
> raw0
[1] 41 42 43 44 00 46
> string0
[1] "ABCD\0F"
> nchar(string0)
[1] 6
> grep("F", string0)
integer(0)
> strsplit(string0, split=NULL, fixed=TRUE)[[1]]
[1] "A" "B" "C" "D"
> tolower(string0)
[1] "abcd"
> chartr("F", "x", string0)
[1] "ABCD"
> substr(string0, 6, 6)
[1] ""
>
> sessionInfo()
R version 2.5.1 (2007-06-27)
powerpc-apple-darwin8.9.1
locale:
en_CA.UTF-8/en_CA.UTF-8/en_CA.UTF-8/C/en_CA.UTF-8/en_CA.UTF-8
attached base packages:
[1] "splines" "stats" "graphics" "grDevices" "utils" "datasets"
"methods" "base"
>
Steven McKinney
Statistician
Molecular Oncology and Breast Cancer Program
British Columbia Cancer Research Centre
email: smckinney +at+ bccrc +dot+ ca
tel: 604-675-8000 x7561
BCCRC
Molecular Oncology
675 West 10th Ave, Floor 4
Vancouver B.C.
V5Z 1L3
Canada
-----Original Message-----
From: [EMAIL PROTECTED] on behalf of Herve Pages
Sent: Tue 8/7/2007 2:06 PM
To: r-devel@r-project.org
Subject: [Rd] Embedded nuls in strings
Hi,
?rawToChar
'rawToChar' converts raw bytes either to a single character string
or a character vector of single bytes. (Note that a single
character string could contain embedded nuls.)
Allowing embedded nuls in a string might be an interesting experiment but it
seems to cause some troubles to most of the string manipulation functions.
A string with an embedded 0:
raw0 <- as.raw(c(65:68, 0 , 70))
string0 <- rawToChar(raw0)
> string0
[1] "ABCD\0F"
nchar() should return 6:
> nchar(string0)
[1] 4
In addition this embedded nul seems to break almost all string
manipulation/searching
functions:
grep("F", string0)
strsplit(string0, split=NULL, fixed=TRUE)[[1]]
tolower(string0)
chartr("F", "x", string0)
substr(string0, 6, 6)
...
etc...
Not very surprisingly, they all seem to treat string0 as if it was "ABCD"!
Cheers,
H.
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