C++语言， 找错问题，请高手帮忙看下，谢谢

#include
using namespace std;

const int size = 3;

class vector
{
public:
int v[size];
public:
vector();
vector(int *x);
friend vector operator *(int b, vector a);
friend istream & operator>> (istream &, vector &);
friend ostream & operator<< (ostream &, vector &);
};

vector::vector()
{
for(int i=0;i {
v[i]=0;
}
}

vector::vector(int *x)
{
for(int i=0;i {
v[i] = x[i];
}
}

vector operator * (int a, vector b)
{
vector c;
for(int i=0;i {
c.v[i]= a * b.v[i];
}
return c;
}

vector operator *(vector b, int a)
{
vector c;
for(int i=0;i {
c.v[i]=b.v[i] * a;
}
return c;
}

istream & operator >> (istream & cin, vector & b)
{
for(int i=0;i {
cin >> b.v[i];
}
return (cin);
}

ostream & operator << (ostream & cout , vector & m)
{
cout << "(" << m.v[0];
for(int i=1;i {
cout << "," << m.v[i];
}
cout << ")";
return (cout);
}

int x[size] = {2,4,6};

int main()
{
vector m;
vector n = x;

cout << "Enter elements of vector m" << endl;
cin >> m;
cout << endl;
cout << "m=" << m << endl;

vector p,q;

p = 2 * m;
q = n * 2;
cout << endl;
cout << "p=" << p << endl;
cout << "q=" << q << endl;

return 0;

}

贴出错误代码，好快速找错啊