Hi Jon,
Jon Clayden wrote:
Hi,
A piece of my code that uses readBin() to read a certain file type is
behaving strangely with R 2.7.0. This seems to be because of a failure
to match() strings after using rawToChar() when the original was
terminated with a "\0" character. Direct equality testing with ==
still works as expected. I can reproduce this as follows:
x <- "foo"
y <- c(charToRaw("foo"),as.raw(0))
z <- rawToChar(y)
z==x
[1] TRUE
z=="foo"
[1] TRUE
z %in% c("foo","bar")
[1] FALSE
z %in% c("foo","bar","foo\0")
[1] FALSE
But this gives TRUE:
> z %in% c("foo","bar", z)
[1] TRUE
An additional problem you have here is that when the "foo\0" string literal
is converted into a character string, then the string data that are after the
first embedded nul are dropped:
> identical("foo\0a\0b", "foo")
[1] TRUE
And to add to the endless source of surprises that come with embedded nuls:
> dump("z", file="")
z <-
"foo\0"
but of course sourcing the above dump into an R session will not restore 'z'.
Dropping support for embedded nuls in R 2.8.0 sounds like good news to me.
Cheers,
H.
But without the nul character it works fine:
zz <- rawToChar(charToRaw("foo"))
zz %in% c("foo","bar")
[1] TRUE
I don't see anything about this in the latest NEWS, but is this
expected behaviour? Or is it, as I suspect, a bug? This seems to be
new to R 2.7.0, as I said.
Regards,
Jon
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