Overloading << and >> operator using friend function implemented in C++

#include<iostream.h>
class complex
{
    private: double real,imag;
    public: complex(){}
              complex(double r,double i)
              {
                    real=r;
                    imag=i;
              }

              friend ostream& operator<<(ostream &s,complex &c);
              friend istream& operator>>(istream &s,complex &c);
};
ostream& operator<<(ostream &s,complex &c)
{
    s<<"("<<c.real<<","<<c.imag<<")";
    return s;
}
istream& operator >> (istream &s,complex &c)
{
    s>>c.real>>c.imag;
    return s;
}
void main()
{
    complex c1(1.5,2.5),c2(3.5,4.5),c3;
    cout<<endl<<"c1="<<c1<<"\nc2="<<c2;
    cout<<endl<<"\n Enter a complex number=";
    cin>>c3;
   cout<<"c3="<<c3;
}