title: Adding function to string class
body: <p>I understand that inheriting from std::string class is a poor idea, but was just trying to add a custom function to string class for a dummy assignment, using inheritance. 
  I want to call my function as 'add' and when I do str.add(str1,str2); it should append str1 at the beginning of the string and str2 at the end of the string. This class(inherited string class) is a private member class of another class(say Parent). when I try to access my string class object with this, it points to the Parent class. How can I do this?</p>
  
  <p>Thanks</p>