#ifndef __COMPLEX_H__
#define __COMPLEX_H__					// prevent multiple inclusion

#include <iostream>					// access: ostream
// NO "using namespace std", use qualification to prevent polluting user's namespace

class Complex {
    friend Complex operator+( Complex a, Complex b );
    friend Complex operator-( Complex a, Complex b );
    friend Complex operator*( Complex a, Complex b );
    friend Complex operator/( Complex a, Complex b );
    friend bool operator==( Complex a, Complex b );
    friend bool operator!=( Complex a, Complex b );
    friend std::istream &operator>>( std::istream &is, Complex &c );
    friend std::ostream &operator<<( std::ostream &os, Complex c );

    double re, im;					// exposed implementation
    static int cplxObjCnt;				// shared counter
  public:
    Complex( double r = 0.0, double i = 0.0 );		// default values only in prototype
    double real() const;				// const means argument object immutable
    double imag() const;
    Complex conjugate() const;
    double abs() const;
    static void stats();				// no "this"
};

extern Complex operator+( Complex a, Complex b );	// allow implicit conversions on both operands
extern Complex operator-( Complex a, Complex b );
extern Complex operator*( Complex a, Complex b );
extern Complex operator/( Complex a, Complex b );
extern bool operator==( Complex a, Complex b );
extern bool operator!=( Complex a, Complex b );
// complex field is unordered so no relational operators, e.g. <, >, <=, >=
extern std::istream &operator>>( std::istream &is, Complex &c );
extern std::ostream &operator<<( std::ostream &os, Complex c );

#endif // __COMPLEX_H__