Faheem Mitha wrote:
SEXP testfn(SEXP chstr) { char * charptr = CHAR(chstr); printf("%s", charptr); }
I am sure I am making an obvious mistake, but can someone help me to sort it out? Thanks in advance. Please cc me, I'm not subscribed.
Firstly, R is expecting an SEXP as a return value! And secondly, your SEXP chstr is still a vector - so you need to get an element from it. If there's only one element, then that'll be the zeroth element. Here's my code:
#include <R.h> #include <Rinternals.h> #include <stdio.h>
SEXP testfn(SEXP chstr)
{
char * charptr = CHAR(VECTOR_ELT(chstr,0));
printf("%s", charptr);
return(chstr);
}- I'm just returning the same object back in the return() statement, and using VECTOR_ELT(chstr,0) to get to the 0'th element.
SO in R:
> foo = .Call("testfn","fnord")should print 'fnord' and return foo as "fnord".
> foo = .Call("testfn",c("bar","baz"))will print 'bar' and return foo as c("bar","baz")Baz
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