Overloading Extractors

To provide custom formatted data retrieval.

  extractor prototype
  Basic_istream &operator >>(basic_istream &s,const imanip<T>&)
  {      // procedures

       return s;
  }
  

You may overload the extractor operator to tailor the specific needs of a particular class.

The this pointer is returned.

#include <iostream>
#include <iomanip>

#include <cstdlib>

#include <cstring>

class phonebook {

   friend std::ostream &operator<<(std::ostream &stream,

      phonebook o);

   friend std::istream &operator>>(std::istream &stream,

      phonebook &o);

   private:

   char name[80];

   int areacode;

   int exchange;

   int num;

   public:

   void putname() {std::cout << num;}

   phonebook() {};    // default constructor

   phonebook(char *n, int a, int p, int nm)

      {std::strcpy(name, n); areacode = a; 

         exchange = p; num = nm;}

};

int main()

{

using namespace std;

   phonebook a;

   cin >> a;

   cout << a;

   return 0; 

}

std::ostream &operator<<(std::ostream &stream, phonebook o)

{

using namespace std;

   stream << o.name << " ";

   stream << "(" << o.areacode << ") ";

   stream << o.exchange << "-";

   cout << setfill('0') << setw(4) << o.num << "\n";

   return stream;

}

std::istream &operator>>(std::istream &stream, phonebook &o)

{

using namespace std;

   char buf[5];

   cout << "Enter the name: ";

   stream >> o.name;

   cout << "Enter the area code: ";

   stream >> o.areacode;

   cout << "Enter exchange: ";

   stream >> o.exchange;

   cout << "Enter number: ";

   stream >> buf;

   o.num = atoi(buf);

   cout << "\n";

   return stream;

}

Result:

  Enter the name: CodeWarrior
  Enter the area code: 512
  Enter exchange: 996
  Enter number: 5300
  CodeWarrior (512) 996-5300