title: Rcpp:CharacterVector size
body: <p>I have been doing some test on Rcpp package and it works great.</p>
  
  <p>I have a little problem when passing some CharacterVector from R to C++.</p>
  
  <pre><code>RcppExport SEXP testArray(SEXP Rarr){
  
          Rcpp::CharacterVector cx(Rarr);
          Rcpp::LogicalVector r(1);
          std::string test = "a";
          r[0] = (*(const char*)cx[0] == *(const char*)test.c_str());
          const char * temp = (const char*)cx;
  
  
          return Rcpp::wrap(temp.size());
  
      }
  </code></pre>
  
  <p>is it possible to get the size of "Rcpp::CharacterVector cx" based on code above?</p>
  
  <p>something like : <strong>cx.size()</strong> or <strong>length(cx)</strong>?</p>
  
  <p>Regards,</p>
  
  <p>Andy</p>