main.cpp

this a good book.

#include <iostream>
#include <cmath>
#include <fstream>
using namespace std;

class Vector2D
{
	double x, y;
public:
	Vector2D(double m=0,double n=0)
	{
		x =m;
		y =n;
	}

	Vector2D operator +(Vector2D& t)
	{
		return Vector2D(x+t.x,y+t.y);
	}
	//* * 1 * *

	{
		return Vector2D(-x,-y);
	}
	//* * 2 * *

	{
		char c;
		is>>c>>f.x>>c>>f.y>>c;
		return is;
	}
	//* * 3 * *

	{
		os<<'('<<f.x<<','<<f.y<<')';
		return os;
	}

};

void main()
{
	Vector2D obj1,obj2;
	cout<<"请输入连个向量,格式(4,2): "<<endl;
	cin>>obj1>>obj2;

	ofstream fp;
	fp.open("abc.txt");

	fp<< obj1 + obj2 << endl;

	//* * 4 * *
	fp<<  << endl;
	fp.close();
}