求兩個向量的內積？

#include <iostream>

using namespace std;

class V

{

double x,y;

public:

V(){}

V(double a,double b)

{

x=a;

y=b;

}

friend V operator*(V a,V b)

{

V c;

c.x=a.x*b.x;

c.y=a.y*b.y;

return c;

}

void show()

{cout<<x<<" "<<y<<endl;}

};

int main()

{

V v1(1,3),v2(2,5),c3;

V *p1,*p2;

p1=&v1;

p2=&v2;

c3=(*p1)*(*p2);

c3.show();

return 0;

}