重载流提取运算符

#include <iostream>
using namespace std;
class Complex
{
public:
 Complex(){real=0;image=0;}
 Complex(int r,int i){real=r;image=i;}
 friend ostream& operator<<(ostream &,Complex &);
 friend istream& operator>>(istream &,Complex &);
private:
 double real;
 double image;
};
ostream& operator<<(ostream &output,Complex &c)
{
 output<<"("<<c.real;
 if(c.image>=0)
  cout<<"+"; 
 cout<<c.image<<"i)";
 return output;
}
istream& operator>>(istream &input,Complex &c)
{
 cout<<"input real part and imaginary part of a complex number:";
 cin>>c.real>>c.image;
 return input;
}
int main()
{
 Complex c1,c2;
 cin>>c1>>c2;
 cout<<"c1="<<c1<<endl;
 cout<<"c2="<<c2<<endl;
 return 0;
}