哪位大哥看看这个C++程序错在哪了

#include<iostream>
#include<string>
using namespace std;

class Vector;
ostream & operator << ( ostream & output,Vector&);
istream & operator >> ( istream & input,Vector&);
class Vector
{
public:
int L;
Vector(int w)
{
vector=new int[w];
L=w;
}
int *vector;
Vector operator +(Vector b)
{
Vector c(b.L);
for (int i=0;i<L;i++)
{
c.vector[i]=vector[i]+b.vector[i];
}
return c;
}
Vector operator -(Vector b)
{
Vector c(b.L);
for (int i=0;i<L;i++)
{
b.vector[i]=vector[i]-b.vector[i];
}
return c;
}
int operator *(Vector b)
{
int temp=0;
for (int i=0;i<L;i++)
{
temp+=(vector[i]*b.vector[i]);
}
return temp;
}

};
ostream & operator<<