Overloading Stream Operators:

4   Stream operators are  “>>” and “<<”.

4   To design manipulator objects, stream operators must be overloaded. 

4   The syntax for input manipulator is:

friend istream& operator >>(istream&, class&);

4   The syntax for output manipulator is:

friend ostream& operator <<(ostream&, class&);

4   Implementing functions of manipulators do not include “friend” keyword.

Example:

class complex

{

  private:

      double r,i;

  public:

    complex() { }

    complex(double rr,double ii) { r=rr; i=ii;}

    friend ostream& operator <<(ostream&,complex&);

    friend istream& operator >>(istream&,complex&);

};

ostream& operator <<(ostream& os,complex& k)

{

    os<<endl<<k.r<<"  "<<k.i<<"i";

    return os;

 }

 istream& operator >>(istream& is,complex& k)

 {

    cout<<endl<<"Enter Real,Imaginary:\n";

    is>>k.r>>k.i;

    return is;

 }

 main()

 {

  complex c1,c2;

  cin>>c1>>c2; 

  cout<<c1<<c2;

 }

Explanation:

The above program uses both input and output manipulators. To read objects “c1” and “c2”, we can simply write “cin>>c1>>c2”. With this, the input manipulator is called and data is read for the data members. Similarly, to print “c1” and “c2”, operator “<<” can be used.