بخش ۹ - سربارگذاری عملگرها

#include <iostream>
using namespace std;

class Complex {
public:
    Complex(double r, double i) : real(r), imag(i) {}
    Complex(double r) : real(r), imag(0) {}
    void print() const;

    Complex add(const Complex& c) const;
    void inc(const Complex& c);

    double re() const { return real; }
    double im() const { return imag; }
private:
    double real;
    double imag;
};

Complex Complex::add(const Complex& c) const {
    return Complex(real + c.real, imag + c.imag);
}

void Complex::inc(const Complex& c) {
    real += c.real;
    imag += c.imag;
}

void Complex::print() const {
    cout << real;
    if (imag > 0)
        cout << '+' << imag << 'i';
    else if (imag < 0)
        cout << imag << 'i';
}

int main() {    
    Complex a(1, 2);
    Complex b(4, -2);

    const Complex zero(0,0);
    zero.inc(a);    // compile error
    zero.print();   // OK!

    a.print();          // 1+2i
    b.print();          // 4-2i

    Complex c = a.add(b);
    c.print();          // 5
    
    b.inc(c);           // 9-2i
    b.print();
}
				

class Complex {
public:
//  Complex add(const Complex& c) const;
    Complex operator+(const Complex& c) const;
//  void inc(const Complex& c);
    Complex& operator+=(const Complex& c);

};

//Complex Complex::add(const Complex& c) const
Complex Complex::operator+(const Complex& c) const
{
    return Complex(real + c.real, imag + c.imag);
}

//void Complex::inc(const Complex& c)
Complex& Complex::operator+=(const Complex& c)
{
    real += c.real;
    imag += c.imag;
    return *this;
}

int main()
{
    Complex a(1, 2);
    Complex b(4, -2);

    // Complex c = a.add(b);
    Complex c = a + b;
    c.print();          // 5
    
    // b.inc(c);            
    b += c;     
    b.print();          // 9-2i
    b.operator+(c);

    (b += c).print();
}
				

class Complex {
public:
    Complex operator+(double r) const;
};

Complex Complex::operator+(double r) const
{
    return Complex(real + r, imag);
}

int main()
{
    Complex a(1, 2);

    Complex c = a + 2;
    c.print();            // 3+2i 
}
				

Complex operator+(const double r, const Complex& c)
{
	return Complex(c.re() + r, c.im());
}

int main()
{
    Complex a(1, 2);

    Complex c = 2 + a;
    c.print();            // 3+2i 
}
				

ostream& operator<<(ostream& out, const Complex& c)
{
    out << c.re();
    if (c.im() > 0)
        out << '+' << c.im() << 'i';
    else if (c.im() < 0)
        out << c.im() << 'i';
        
    return out;
}

int main()
{
    Complex a(1, 2);
    Complex b(4, -2);

    cout << a << b << endl;
}
				

class Complex {
    friend ostream& operator<<(ostream& out, const Complex& c);
};

ostream& operator<<(ostream& out, const Complex& c)
{
    out << c.real;
    if (c.imag > 0)
        out << '+' << c.imag << 'i';
    else if (c.imag < 0)
        out << c.imag << 'i';

    return out;
}