#include <iostream>
using namespace std;

class BString
{
   friend ostream& operator<< (ostream& os, const BString& s);
   friend istream& operator>> (istream& os, BString& s);

   friend BString operator+(const BString& x, const BString& y);

   friend bool operator< (const BString& x, const BString& y);
   friend bool operator> (const BString& x, const BString& y);
   friend bool operator<=(const BString& x, const BString& y);
   friend bool operator>=(const BString& x, const BString& y);
   friend bool operator==(const BString& x, const BString& y);
   friend bool operator!=(const BString& x, const BString& y);

public:
   BString();			// init to empty string
   BString(const char* s);	// conversion from c-string
   BString(int x);		// conversion from int to Bstring

   ~BString();			// destructor
   BString(const BString& s);			// copy constructor (deep copy)
   BString& operator=(const BString& s);	// operator= (deep copy)

   BString& operator+=(const BString& s);


   void Display() const;			// print the string
   int length() const;				// return the length of the string

   BString substring(int index, int len);	// return substring of this string


private:
   char* str;		// a pointer to our dynamic array of char
   int size;		// the size (length) of my string.
			//    allocation will be exactly what is needed
};