// FIG8_3.CPP
// Overloading the stream-insertion and 
// stream-extraction operators.
#include <iostream.h>

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
};

// Overloaded stream insertion operator (cannot be 
// a member function).
ostream &operator<<(ostream &output, const PhoneNumber &num)
{
   output << "(" << num.areaCode << ") "
          << num.exchange << "-" << num.line;

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

// overloaded stream extraction operator
istream &operator>>(istream &input, PhoneNumber &num)
{
   input.ignore();                 // skip (
   input.getline(num.areaCode, 4); // input area code
   input.ignore(2);                // skip ) and space
   input.getline(num.exchange, 4); // input exchange
   input.ignore();                 // skip dash (-)
   input.getline(num.line, 5);     // input line

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

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

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

   // cin >> phone invokes operator>> function by 
   // issuing the call operator>>(cin, phone).
   cin >> phone;

   // cout << phone invokes operator<< function by
   // issuing the call operator<<(cout, phone). 
   cout << "The phone number entered was:" << endl
        << phone << endl;
   return 0;
}
---------------------------------------------------
// ARRAY1.H
// Simple class Array (for integers)
#ifndef ARRAY1_H
#define ARRAY1_H

#include <iostream.h>

class Array {
   friend ostream &operator<<(ostream &, const Array &);
   friend istream &operator>>(istream &, Array &);
public:
   Array(int = 10);                     // default constructor
   Array(const Array &);                // copy constructor
   ~Array();                            // destructor
   int getSize() const;                 // return size
   const Array &operator=(const Array &);  // assign arrays
   int operator==(const Array &) const; // compare equal
   int operator!=(const Array &) const; // compare !equal
   int &operator[](int);                // subscript operator
   static int getArrayCount();          // Return count of 
                                        // arrays instantiated.
private:
   int *ptr; // pointer to first element of array
   int size; // size of the array
   static int arrayCount;  // # of Arrays instantiated
};

#endif
---------
// ARRAY1.CPP
// Member function definitions for class Array
#include <iostream.h>
#include <stdlib.h>
#include <assert.h>
#include "array1.h"

// Initialize static data member at file scope
int Array::arrayCount = 0;   // no objects yet

// Default constructor for class Array
Array::Array(int arraySize)
{
   ++arrayCount;             // count one more object
   size = arraySize;         // default size is 10
   ptr = new int[size];      // create space for array
   assert(ptr != 0);  // terminate if memory not allocated

   for (int i = 0; i < size; i++)
      ptr[i] = 0;            // initialize array
}

// Copy constructor for class Array
Array::Array(const Array &init)
{
   ++arrayCount;             // count one more object
   size = init.size;         // size this object
   ptr = new int[size];      // create space for array
   assert(ptr != 0);  // terminate if memory not allocated

   for (int i = 0; i < size; i++)
      ptr[i] = init.ptr[i];  // copy init into object
}

// Destructor for class Array
Array::~Array()
{
   --arrayCount;             // one fewer objects
   delete [] ptr;            // reclaim space for array
}

// Get the size of the array
int Array::getSize() const { return size; }

// Overloaded assignment operator
const Array &Array::operator=(const Array &right)
{
   if (&right != this) {    // check for self-assignment
      delete [] ptr;        // reclaim space
      size = right.size;    // resize this object
      ptr = new int[size];  // create space for array copy
      assert(ptr != 0);     // terminate if memory not allocated

      for (int i = 0; i < size; i++)
         ptr[i] = right.ptr[i];  // copy array into object
   }

   return *this;   // enables x = y = z;
}

// Determine if two arrays are equal and
// return 1 if true, 0 if false.
int Array::operator==(const Array &right) const
{
   if (size != right.size)
      return 0;    // arrays of different sizes

   for (int i = 0; i < size; i++)
      if (ptr[i] != right.ptr[i])
         return 0; // arrays are not equal

   return 1;       // arrays are equal
}

// Determine if two arrays are not equal and
// return 1 if true, 0 if false.
int Array::operator!=(const Array &right) const
{
   if (size != right.size)
      return 1;         // arrays of different sizes

   for (int i = 0; i < size; i++)
      if (ptr[i] != right.ptr[i])
         return 1;      // arrays are not equal

   return 0;            // arrays are equal
}

// Overloaded subscript operator
int &Array::operator[](int subscript)
{
   // check for subscript out of range error
   assert(0 <= subscript && subscript < size);

   return ptr[subscript];   // reference return creates lvalue
}

// Return the number of Array objects instantiated
int Array::getArrayCount() { return arrayCount; }

// Overloaded input operator for class Array;
// inputs values for entire array.
istream &operator>>(istream &input, Array &a)
{
   for (int i = 0; i < a.size; i++)
      input >> a.ptr[i];

   return input;   // enables cin >> x >> y;
}

// Overloaded output operator for class Array
ostream &operator<<(ostream &output, const Array &a)
{
   for (int i = 0; i < a.size; i++) {
      output << a.ptr[i] << ' ';

      if ((i + 1) % 10 == 0)
         output << endl;
   }

   if (i % 10 != 0)
      output << endl;

   return output;   // enables cout << x << y;
}
---------------
// FIG8_4.CPP
// Driver for simple class Array
#include <iostream.h>
#include "array1.h"

main()
{
   // no objects yet
   cout << "# of arrays instantiated = "
        << Array::getArrayCount() << endl;

   // create two arrays and print Array count
   Array integers1(7), integers2;
   cout << "# of arrays instantiated = "
        << Array::getArrayCount() << endl << endl;

   // print integers1 size and contents
   cout << "Size of array integers1 is "
        << integers1.getSize() << endl
        << "Array after initialization:" << endl
        << integers1 << endl;

   // print integers2 size and contents
   cout << "Size of array integers2 is "
        << integers2.getSize() << endl
        << "Array after initialization:" << endl
        << integers2 << endl;

   // input and print integers1 and integers2
   cout << "Input 17 integers:" << endl;
   cin >> integers1 >> integers2;
   cout << "After input, the arrays contain:" << endl
        << "integers1: " << integers1
        << "integers2: " << integers2 << endl;

   // use overloaded inequality (!=) operator
   cout << "Evaluating: integers1 != integers2" << endl;
   if (integers1 != integers2)
      cout << "They are not equal" << endl;

   // create array integers3 using integers1 as an
   // initializer; print size and contents
   Array integers3(integers1);

   cout << endl << "Size of array integers3 is "
        << integers3.getSize() << endl
        << "Array after initialization:" << endl
	<< integers3 << endl;

   // use overloaded assignment (=) operator
   cout << "Assigning integers2 to integers1:" << endl;
   integers1 = integers2;
   cout << "integers1: " << integers1
        << "integers2: " << integers2 << endl;

   // use overloaded equality (==) operator
   cout << "Evaluating: integers1 == integers2" << endl;
   if (integers1 == integers2)
      cout << "They are equal" << endl << endl;

   // use overloaded subscript operator to create rvalue
   cout << "integers1[5] is " << integers1[5] << endl;

   // use overloaded subscript operator to create lvalue
   cout << "Assigning 1000 to integers1[5]" << endl;
   integers1[5] = 1000;
   cout << "integers1: " << integers1 << endl;

   // attempt to use out of range subscript
   cout << "Attempt to assign 1000 to integers1[15]" << endl;
   integers1[15] = 1000;  // ERROR: out of range

   return 0;
}