string:: resolution scope to _type

// stoi example
#include <iostream>   // std::cout
#include <string>     // std::string, std::stoi
using namespace std;
int main ()
{
  string str_dec = "2001, A Space Odyssey";
  string str_hex = "40c3";
  string str_bin = "-10010110001";
  string str_auto = "0x7f";

  string::size_type sz;   // alias of size_t

  int i_dec = std::stoi (str_dec,&sz);
  int i_hex = std::stoi (str_hex,nullptr,16);
  int i_bin = std::stoi (str_bin,nullptr,2);
  int i_auto = std::stoi (str_auto,nullptr,0);

  cout << str_dec << ": " << i_dec << " and [" << str_dec.substr(sz) << "]\n";
  cout << str_hex << ": " << i_hex << '\n';
  cout << str_bin << ": " << i_bin << '\n';
  cout << str_auto << ": " << i_auto << '\n';

  return 0;
}