C++基本语法---重载二元运算符

#include <iostream>
using namespace std;

class Box{
	public :
	double getVolume(){
		return length * breadth * height;
	}
	
	void setLength(double len){
		length = len;
	}
	
	void setBreadth(double brea){
		breadth = brea;
	}
	
	void setHeight(double hei){
		height = hei;
	}
	
	Box operator+(const Box &b){
		Box box;
		box.length = this->length + b.length;
		box.breadth = this->breadth + b.breadth;
		box.height = this->height + b.height;
		return box;
	}
	
	private:
	double length;
	double breadth;
	double height;
};

int main()
{	
	Box box1, box2, box3;
	
	box1.setLength(1.0);
	box1.setBreadth(2.0);
	box1.setHeight(3.0);
	
	box2.setLength(4.0);
	box2.setBreadth(5.0);
	box2.setHeight(6.0);
	
	box3 = box1 + box2;
	
	cout << "box3的volume:" << box3.getVolume() << endl;
	
	
    return 0;
}