http://stackoverflow.com/questions/43182003/concatenate-stringvector-with-rcpp

ModifyString.cpp

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
CharacterVector ModifyString(CharacterVector x)
{
    String ref = x[0];
    ref = "Modified";
    return x;
}

// [[Rcpp::export]]
CharacterVector ModifyProxy(CharacterVector x)
{
    internal::string_proxy<STRSXP> ref = x[0];
    ref = "Modified";
    return x;
}

/*** R

x <- letters[1:5]

ModifyString(x)
# [1] "a" "b" "c" "d" "e"

ModifyProxy(x)
# [1] "Modified" "b"        "c"        "d"        "e"

*/