text: #include <iostream>
  #include <string>
  #include <cstring>
  using std::cout; using std::endl; using std::string;
  
  int main()
  {
      // use string.
      string s1("Mooophy"), s2("Pezy");
      if (s1 == s2)
          cout << "same string." << endl;
      else if (s1 > s2)
          cout << "Mooophy > Pezy" << endl;
      else
          cout << "Mooophy < Pezy" << endl;
  
      cout << "=========" << endl;
  
      // use C-Style character strings.
      const char* cs1 = "Wangyue";
      const char* cs2 = "Pezy";
      auto result = strcmp(cs1, cs2);
      if (result == 0)
          cout << "same string." << endl;
      else if (result < 0)
          cout << "Wangyue < Pezy" << endl;
      else
          cout << "Wangyue > Pezy" << endl;
  
      return 0;
  }
  