c++重载ostream的实现

#include <iostream>
using namespace std;

class Point{
public:
	Point(int _x = 0, int _y = 0, int _z = 0):x(_x), y(_y), z(_z){}
	Point(){}
	~Point(){}
	friend ostream& operator<<(ostream &os, const Point &pd);
private:
	int x;
	int y;
	int z;
};

ostream& operator<<(ostream &os, const Point &pd){
	os << pd.x<<" "<<pd.y<<" "<<pd.z;
	return os;
}

int main() {
	Point pd(1,2,3);
	cout<<pd;
	return 0;
}

主要的注意点就是，要把函数作为class Point的友元函数，在类的外面进行定义，此外要注意return os，达到链式的作用。