test_src.cpp

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
SEXP with_string(CharacterVector names) {
  int size = names.size();
  std::vector<String> tmp;
  String strtmp;
  CharacterVector out_vec(tmp.begin(), tmp.end());
  
  for (int i = 0; i < size; ++i) {
    strtmp = names[i];
    tmp.push_back(strtmp);
  }
  
  return out_vec;
}

// [[Rcpp::export]]
SEXP with_stdstr(CharacterVector names) {
  int size = names.size();
  std::vector<std::string> tmp;
  String strtmp;
  CharacterVector out_vec(tmp.begin(), tmp.end());
  
  for (int i = 0; i < size; ++i) {
    strtmp = names[i];
    tmp.push_back(strtmp);
  }
  
  return out_vec;
}


/*** R
system.time(a <- with_string(paste0("col_", 1:50000)))
system.time(b <- with_stdstr(paste0("col_", 1:50000)))
identical(a, b)
*/