#include <iostream>
#include <string>

using namespace std;

struct mystr {
  void buildstr(string aString); // public
  void showstr();
private: // by default struct fields and functions are public
  string myString;
};

void mystr::buildstr(string theString) {
  if(theString == "") {
    myString = ""; // init string
  } else {
    myString = myString + theString;
  }
}

void mystr::showstr() {
  cout << myString << "\n";
}

int main() {
  mystr s;

  s.buildstr("");
  s.buildstr("Hello ");
  s.buildstr("there!");

  s.showstr();

  return 0;
}