[Rcpp-devel] Call by reference

[Rguy]

I attempted to implement the call by reference example on page 200 of
Seamless R and C++, as follows:

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
void absC(double & x) {
if (x < 0) x = -x;
}

/*** R
x = -1
absC(x)
x
*/

Unfortunately, x remains equal to -1.
Platforms: Windows 7,  "R version 3.1.3 Patched (2015-03-16 r68103)".
Please advise.
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