Allocate an array of objects by overloading new and delete operators : new « Development « C++ Tutorial

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#include <iostream>
#include <cstdlib>
#include <new>
using namespace std;

class Point {
  int x, y;
public:
  Point() {x = y = 0;}
  Point(int px, int py) {
    x = px;
    y = py;
  }

  void show() {
    cout << x << " ";
    cout << y << "\n";
  }

  void *operator new(size_t size);
  void operator delete(void *p);

  void *operator new[](size_t size);
  void operator delete[](void *p);
};

// new overloaded relative to Point.
void *Point::operator new(size_t size)
{
void *p;

  cout << "In overloaded new.\n";
  p =  malloc(size);
  if(!p) {
    bad_alloc ba;
    throw ba;
  }
  return p;
}

// delete overloaded relative to Point.
void Point::operator delete(void *p)
{
  cout << "In overloaded delete.\n";
  free(p);
}

// new overloaded for Point arrays.
void *Point::operator new[](size_t size)
{
  void *p;

  cout << "Using overload new[].\n";
  p =  malloc(size);
  if(!p) {
    bad_alloc ba;
    throw ba;
  }
  return p;
}

// delete overloaded for Point arrays.
void Point::operator delete[](void *p)
{
  cout << "Freeing array using overloaded delete[]\n";
  free(p);
}

int main()
{
  Point *p1, *p2;
  int i;

  try {
    p1 = new Point (10, 20); // allocate an object
  } catch (bad_alloc xa) {
    cout << "Allocation error for p1.\n";
    return 1;;
  }

  try {
    p2 = new Point [10]; // allocate an array
  } catch (bad_alloc xa) {
    cout << "Allocation error for p2.\n";
    return 1;;
  }

  p1->show();

  for(i=0; i<10; i++)
    p2[i].show();

  delete p1; // free an object
  delete [] p2; // free an array

  return 0;
}

In overloaded new.
Using overload new[].
10 20
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
0 0
In overloaded delete.
Freeing array using overloaded delete[]