Le 29/09/13 14:06, Simon Zehnder a écrit :
Dear Rcpp::Users and Rcpp::Devels,
I would like to understand a certain behaviour of my code I encountered lately.
I am working with CharacterVector and the following behaviour occurred:
void test1 (Rcpp::CharacterVector &charv)
{
Rprintf("test1: %s\n", (char*) charv(0));
}
void test2 (const Rcpp::CharacterVector &str)
{
Rprintf("test2: %s\n", (char*) charv(0));
}
Try actually using the variable you pass in, as in:
void test2 (const Rcpp::CharacterVector &str)
{
Rprintf("test2: %s\n", (char*) str(0));
}
Although it still exposes the bug.
You can use something like this in the meantime:
void test2 (const Rcpp::CharacterVector& charv)
{
String x = charv[0] ;
Rprintf("test2: %s\n", x.get_cstring());
}
It looks like the bug is about converting the result of charv(0) to a
char*. Probably worth looking at the string_proxy class.
Romain
Using a string like "2013-05-04 20:23:21" for the Rcpp::CharacterVector gives
the following outputs:
test1: 2013-05-04 20:23:21
test2: `
This does also not change if I use a cast to const char* in test2. I tried
something similar with strings and printing the c_str() of them, there the
'const' keyword does not make a difference - it always prints the correct
string.
Is this something specific to the Rcpp::CharacterVector, that uses a
string_proxy for its elements returned by the operator ()? Is there a way to
use const Rcpp::CharacterVector and get the behaviour of test1?
Best
Simon
--
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30
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