Can reference be compared with pointer?

Question

I'm studying Copy assignment in C++. If you see the line 5 at the code below, there is "this == &rhs". Is this expression legal? this is a pointer to an obejct and rhs is an reference to object. So it is different. Or Can reference be compared with pointer? Thank you.

class Mystring{
  //class
};

Mystring& Mystring::operator=(const Mystring &rhs){
  if (this==&rhs)   //<===========this line
    return *this;

  delete [] str;
  str = new char[std::strlen(rhs.str)+1];
  std::strcpy(str, rhs.str);

  return *this;
}

Answer 1

there is "this == &rhs". Is this expression legal?

Yes.

this is a pointer to an obejct and rhs is an reference to object. So it is different.

Yes.

Or Can reference be compared with pointer?

Potentially yes (if the reference is to a class type with an operator overload for comparing with a pointer), but that's not what the example program does because it doesn't compare pointer with rhs. The example programs a pointer with &rhs which is also a pointer.

Answer 2

there is "this == &rhs". Is this expression legal?

Yes it is.

Just a sidenote, References are aliasses to another variable.

Also a quick optimization of the code below:

Mystring& Mystring::operator=(const Mystring &rhs){
   if (this != &rhs)
   {
      delete [] str;
      str = new char[std::strlen(rhs.str)+1];
      std::strcpy(str, rhs.str);
   }
return *this;
}