侯捷C++学习（二）

#include <iostream>
using namespace std;
class complex
{
public:
complex (double r= 0, double i = 0)
:re (r) , im(i)
{ }
complex operator += (const complex& c)
{
this->re = c.re + this->re;
this->im = c.im + this->im;
return * this;
}
double real () const {return re;}
double imag () const {return im;}
private:
double re,im;
friend complex&_dopal (complex*,const complex&);
};
ostream & operator<< (ostream & os, const complex& x)
{
return os<< '(' << x.real () <<','
<< x.imag () <<'(';
}
//尽量不要 pass by value 引用就是一个指针
int main()
{
complex c(1,2), d(2,3),e(1,1),a(5,5);
a += c += d;
cout << a;
return 0;
}