+=,-=重载

using namespace std;

class Complex
{
public:
	Complex(int a, int b)
	{
		this->a = a;
		this->b = b;
	}

	friend Complex & operator+=(Complex &c1, Complex &c2);
	friend Complex &operator-=(Complex &c1, Complex &c2);

	Complex &operator+=(Complex &another)
	{
		this->a += another.a;
		this->b += another.b;
		return *this;
	}
private:
	int a;
	int b;
	};

//全局
Complex & operator+=(Complex &c1, Complex &c2)
{
	c1.a += c2.a;
	c1.b += c2.b;

	return c1;
}

Complex &operator-=(Complex &c1, Complex &c2)
{
	c1.a -= c2.a;
	c1.b -= c2.b;

	return c1;
}

int main(void)
{
	Complex c1(1, 2);
	Complex c2(2, 4);

	(c1 += c2)+=c2;//c1.operator+=(c2)  .operator(c2)
	
	return 0;
}