C++关于二维向量的乘法问题

[gaoshou0804]

#include <iostream>
using namespace std;
class Vector2D
{
public:
int x1,x2,y1,y2;
void input1()
{
cout<<"Please input the x1 of the A(x1,x2) "<<endl;
cin>>x1;
cout<<"Please input the x2 of the A(x1,x2) "<<endl;
cin>>x2;

}
void input2()
{
cout<<"Please input the y1 of the B(y1,y2) "<<endl;
cin>>y1;
cout<<"Please input the y2 of the B(y1,y2) "<<endl;
cin>>y2;
}
int Multiply(int x1,int x2,int y1,int y2)
{
return x1*x2+y1*y2;
}
};

int main()
{ Vector2D v;
v.input1();
v.input2();
int Vector2D::Multiply(int x1,int x2,int y1,int y2);
}

让写一个类，来执行向量的乘法运算。。。请问为何没有输出。。应该怎么改啊。。。。。

[淡蓝]

class Vector2D
{
public:
int x1,x2,y1,y2;
void input1()
{
cout<<"Please input the x1 of the A(x1,x2) "<<endl;
cin>>x1;
cout<<"Please input the x2 of the A(x1,x2) "<<endl;
cin>>x2;

}
void input2()
{
cout<<"Please input the y1 of the B(y1,y2) "<<endl;
cin>>y1;
cout<<"Please input the y2 of the B(y1,y2) "<<endl;
cin>>y2;
}
int Multiply()
{
return x1*x2+y1*y2;
}
};

[淡蓝]

把类改一下

[newfarmerchi]

#include <iostream>
using namespace std;
class Vector2D
{
  public:
  int x1,x2,y1,y2;
  void input1()
  {
  cout<<"Please input the x1 of the A(x1,x2) "<<endl;
  cin>>x1;
  cout<<"Please input the x2 of the A(x1,x2) "<<endl;
  cin>>x2;

  }
  void input2()
  {
  cout<<"Please input the y1 of the B(y1,y2) "<<endl;
  cin>>y1;
  cout<<"Please input the y2 of the B(y1,y2) "<<endl;
  cin>>y2;
  }
  int Multiply()//<---------here
  {
  return x1*x2+y1*y2;
  }
};

int main()
{ Vector2D v;
  v.input1();
  v.input2();
 cout<<v.Multiply()<<endl;//<--------------here
}