array.cpp

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// Fig 11.7: Array.cpp
// Member-function definitions for class Array
#include <iostream>
using std::cout;
using std::cin;
using std::endl;

#include <iomanip>
using std::setw;

#include <new> // C++ standard "new" operator
#include <cstdlib> // exit function prototype
#include "Array.h" // Array class definition

// default constructor for class Array (default size 10)
Array::Array( int arraySize )
{
   size = ( arraySize > 0 ? arraySize : 10 ); // validate arraySize
   ptr = new int[ size ]; // create space for pointer-based array

   for ( int i = 0; i < size; i++ )
      ptr[ i ] = 0; // initialize pointer-based array element
} // end Array default constructor

// copy constructor for class Array;
// must receive a reference to prevent infinite recursion
Array::Array( const Array &arrayToCopy ) 
   : size( arrayToCopy.size )
{
   ptr = new int[ size ]; // create space for pointer-based array

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

// destructor for class Array
Array::~Array()
{
   delete [] ptr; // reclaim pointer-based array space
} // end destructor

// return number of elements of Array
int Array::getSize() const
{
   return size; // number of elements in Array
} // end function getSize

// overloaded assignment operator;
// const return avoids: ( a1 = a2 ) = a3
const Array &Array::operator=( const Array &right )
{
   if ( &right != this ) // avoid self-assignment
   {
      // for Arrays of different sizes, deallocate original
      // left-side array, then allocate new left-side array
      if ( size != right.size )
      {
         delete [] ptr; // reclaim space
         size = right.size; // resize this object
         ptr = new int[ size ]; // create space for array copy
      } // end inner if

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

   return *this; // enables x = y = z, for example
} // end function operator=

// determine if two Arrays are equal and
// return true, otherwise return false
bool Array::operator==( const Array &right ) const
{
   if ( size != right.size )
      return false; // arrays of different number of elements

   for ( int i = 0; i < size; i++ )
      if ( ptr[ i ] != right.ptr[ i ] )
         return false; // Array contents are not equal
   return true; // Arrays are equal
} // end function operator==

// overloaded subscript operator for non-const Arrays;
// reference return creates an lvalue
int &Array::operator[]( int subscript )
{
   // check for subscript out of range error
   if ( subscript < 0 || subscript >= size )
   {
      cout << "\nError: Subscript " << subscript 
         << " out of range" << endl;
      exit( 1 ); // terminate program; subscript out of range
   } // end if

   return ptr[ subscript ]; // reference return
} // end function operator[]

// overloaded subscript operator for const Arrays
// const reference return creates an rvalue
const int &Array::operator[]( int subscript ) const
{
   // check for subscript out of range error
   if ( subscript < 0 || subscript >= size )
   {
      cout << "\nError: Subscript " << subscript 
         << " out of range" << endl;
      exit( 1 ); // terminate program; subscript out of range
   } // end if

   return ptr[ subscript ]; // const reference return
} // end function operator[]

// 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;
} // end function 

// overloaded output operator for class Array 
ostream &operator<<( ostream &output, const Array &a )
{
   int i;

   // output private ptr-based array 
   for ( i = 0; i < a.size; i++ )
   {
      output << setw( 12 ) << a.ptr[ i ];

      if ( ( i + 1 ) % 4 == 0 ) // 4 numbers per row of output
         output << endl;
   } // end for

   if ( i % 4 != 0 ) // end last line of output
      output << endl;

   return output; // enables cout << x << y;
} // end function operator<<

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