First, we design the representation of Vector and Point, and then perfect the constructors in the two classes in turn, copy the constructors and so on.

The vector is represented by two points. When the operation is performed, the coordinate of the starting point is (0, 0).

Line 14: since Vector needs to use x,y in Point, it is more convenient to design it as friend.

Line 13: because the ostream and istream classes cannot be modified, overload "<" > "as a global function or declare it as a friend; return os can realize the continuous use of" < ">";

Line 49: design the second constructor to implement the return value when the operator in Vector is overloaded;

Line 59: prevent self replication;

 1 #include<iostream>
 2 using namespace std;
 3 
 4 class Point        // Point class 
 5 {
 6     private :
 7         double x,y;
 8     public :    
 9         Point(double x1=0,double y1=0):x(x1),y(y1) {}     // Point Constructor 
10         Point(const Point &rhs);        // Point copy constructor  
11         Point operator + (const Point & a);        // Point + 
12         Point operator - (const Point & a);        // Point - 
13         friend ostream & operator << (ostream & os , const Point & a);    // Point Output overload 
14         friend class Vector;    // Friends 
15 };
16 
17 Point::Point(const Point & rhs)        // Point copy constructor 
18 {
19     if(this != &rhs)
20     {
21         x = rhs.x;
22         y = rhs.y;        
23     }
24 }
25 
26 Point Point::operator + (const Point & a)    // Point + 
27 {
28     return Point(x + a.x , y + a.y);
29 } 
30 
31 Point Point::operator - (const Point & a)    // Point -
32 {
33     return Point(x - a.x , y - a.y);
34 }
35 
36 ostream & operator << (ostream & os , const Point & a)        // Point << 
37 {
38     os <<a.x<<","<<a.y;
39     return os;
40 }
41 
42 class Vector     // Vector class 
43 {
44     private :
45         Point beg,end,_00;
46     public :
47         Vector(double x1=0,double y1=0,double x2=0,double y2=0)        // Constructor 1 
48             :beg(x1,y1),end(x2,y2) {} 
49         Vector(Point beg1,Point end1):beg(beg1),end(end1) {}    // Constructor 2 (overload)
50         Vector(const Vector & b);        // copy constructor  
51         Vector operator + (const Vector & b);        // Vector + 
52         Vector operator - (const Vector & b);        // Vector -
53         friend ostream & operator << (ostream & os , const Vector & b);        // Vector Output overload << 
54 //        void print();            // Output function          
55 };
56 
57 Vector::Vector(const Vector & rhs1)        // copy constructor  
58 {
59     if(this != &rhs1)
60     {
61     beg = rhs1.beg;
62     end = rhs1.end;        
63     }
64 } 
65 
66 Vector Vector::operator + (const Vector & b)        // Vector + 
67 {
68     return Vector(_00 , end  -beg + b.end - b.beg);        // Construct with constructor overload 
69 } 
70 
71 Vector Vector::operator - (const Vector & b)    // Vector -
72 {
73     return Vector(_00 , end - beg - b.end + b.beg);
74 }
75 /*
76 void Vector::print()    // Output function 
77 {
78     cout <<"("<<beg.x<<","<<beg.y<<")"<<"\t";
79     cout <<"("<<end.x<<","<<end.y<<")"<<endl<<endl;
80 }
81 */
82 
83 ostream & operator << (ostream & os , const Vector & b)
84 {
85     os <<"("<<b.beg<<")"<<"\t";
86     os <<"("<<b.end<<")"<<endl<<endl;
87     return os;
88 }
89 
90 int main()
91 {
92     Vector ww(0,0,10,10),mm(1,1,5,5);
93 //    ww.print();
94 //    mm.print();
95 //    (ww+mm).print();
96 //    (ww-mm).print();
97     cout<<ww<<mm<<ww-mm<<mm+ww;
98     return 0;
99 }

2019-10-17