C++ Operator Overload '==' operator compares strings

#include <iostream>
using namespace std;
#include <string.h>      //for strcmp()
class String             //user-defined string type
{
   private:/*  w  w w.  jav  a2  s  . co  m*/
   enum { SZ = 80 };                //size of String objects
   char str[SZ];                    //holds a string
   public:
   String()                         //constructor, no args
   { strcpy(str, ""); }
   String( char s[] )               //constructor, one arg
   { strcpy(str, s); }
   void display() const
   { cout << str; }
   void getstr()
   { cin.get(str, SZ); }
   bool operator == (String ss) const  //check for equality
   {
      return ( strcmp(str, ss.str)==0 ) ? true : false;
   }
};
int main()
{
   String s1 = "yes";
   String s2 = "no";
   String s3;
   cout << "\nEnter 'yes' or 'no': ";
   s3.getstr();                        //get String from user
   
   if(s3==s1)                          //compare with "yes"
      cout << "You typed yes\n";
   else if(s3==s2)                     //compare with "no"
       cout << "You typed no\n";
   else
      cout << "You didn't follow instructions\n";
   return 0;
}