// Complex Class as given in Ch. 4 of A Tour of C++, Bjarne Stroustrup, (both 2014 & 2018)

// partial implementation, with differences from Stroustrup's version

class complex {
   double _real_part, _imaginary_part;
public:
   complex(double r = 0, double i = 0) : _real_part{r}, _imaginary_part{i} { }

   double real() const { return _real_part; }
   double imaginary() const { return _imaginary_part; }

   complex& operator=(complex other) {
      _real_part = other._real_part;
      _imaginary_part = other._imaginary_part;
      return *this;
   }

   complex& operator+=(complex other) {
      _real_part += other._real_part;
      _imaginary_part += other._imaginary_part;
      return *this;
   }
};

complex operator+(complex a, complex b) {
   complex result;
   result = a;
   result += b;
   return result;
}

// DANGEROUS definition of ==
bool operator==(complex a, complex b) {
   return a.real() == b.real() && a.imaginary() == b.imaginary();
}