// 8. Предефиниране на операции - основни понятия и ограничения. 
//    Функции за предефиниране - членове или приятелски функции. 
//    Предефиниране на входен и изходен поток. 
//
// Операции в С++, които могат да се предефинират
// +    -    *    /    %    ^    &    |  
//  ~    !    =    <    >    +=   -=   *=
// /=   %=   ^=   &=   |=   <<   >>   >>=
// <<=  ==   !=   <=   >=   &&   ||   ++
// --   ->*  ,    ->   []   ()   new  delete
// new[] delete[]
//
// Операции в С++, които НЕ могат да се предефинират
// .    .*   ::    ?:    sizeof
/**************************************************/
// Fig. 8.3: fig08_03.cpp
// Overloading the stream-insertion and 
// stream-extraction operators.
#include <iostream>

using std::cout;
using std::cin;
using std::endl;
using std::ostream;
using std::istream;

#include <iomanip>

using std::setw;

// PhoneNumber class definition
class PhoneNumber {
   friend ostream &operator<<( ostream&, const PhoneNumber & );
   friend istream &operator>>( istream&, PhoneNumber & );

private:
   char areaCode[ 4 ];  // 3-digit area code and null
   char exchange[ 4 ];  // 3-digit exchange and null
   char line[ 5 ];      // 4-digit line and null

}; // end class PhoneNumber

// overloaded stream-insertion operator; cannot be 
// a member function if we would like to invoke it with
// cout << somePhoneNumber;
ostream &operator<<( ostream &output, const PhoneNumber &num )
{
   output << "(" << num.areaCode << ") "
          << num.exchange << "-" << num.line;

   return output;     // enables cout << a << b << c;

} // end function operator<< 

// overloaded stream-extraction operator; cannot be 
// a member function if we would like to invoke it with
// cin >> somePhoneNumber;
istream &operator>>( istream &input, PhoneNumber &num )
{
   input.ignore();                     // skip (
   input >> setw( 4 ) >> num.areaCode; // input area code
   input.ignore( 2 );                  // skip ) and space
   input >> setw( 4 ) >> num.exchange; // input exchange
   input.ignore();                     // skip dash (-)
   input >> setw( 5 ) >> num.line;     // input line

   return input;      // enables cin >> a >> b >> c;

} // end function operator>> 

int main()
{
   PhoneNumber phone; // create object phone

   cout << "Enter phone number in the form (123) 456-7890:\n";

   // cin >> phone invokes operator>> by implicitly issuing
   // the non-member function call operator>>( cin, phone )
   cin >> phone;

   cout << "The phone number entered was: ";

   // cout << phone invokes operator<< by implicitly issuing 
   // the non-member function call operator<<( cout, phone )
   cout << phone << endl;

   return 0;

} // end main
/*****************************************************/