Организация кода, вывод строки в консоли, использование extern

// TestCpp.h
using namespace std;
 
extern settings set;
 
bool TestCpp()
{
  string strsum = set.param1 + set.param2;
  cout << strsum << endl;
  return(EXIT_SUCCESS);
}
// ReadSettings.h
#ifndef READ_SETTINGS
#define READ_SETTINGS
#endif
 
#include <exception>
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/xml_parser.hpp>
 
using namespace std;
 
struct settings
{
  string param1; 
  string param2;
  int param3;
  int param4;
  double param5;
  double param6;
  void load(const string &filename);
};
 
void settings::load(const string &filename)
{
  using boost::property_tree::ptree;
  ptree pt;
  read_xml(filename, pt);
  param1 = pt.get<std::string>("settings.param1");
  param2 = pt.get<std::string>("settings.param2");
  param3 = pt.get("settings.param3", 0);
  param4 = pt.get("settings.param4", 0);
  param5 = pt.get("settings.param5", 0.0);
  param6 = pt.get("settings.param6", 0.0);
}
// TestCppMain.h
#include <windows.h>
#include <iostream>
#include "ReadSettings.h"
#include "TestCpp.h"
 
settings set;
 
int main()
{
  setlocale(LC_ALL, "Russian");
  try
  {
    set.load("settings.xml");
  }
  catch (std::exception &e)
  {
    std::cout << "Error: " << e.what() << "\n";
    cin.get();
    exit(1);
  }
  TestCpp();
  cout << "Программа завершена!" << endl;
  cin.get();
}