An example of overloading new and delete globally : overload new operator « Operator Overloading « C++ Tutorial

1. C++ Tutorial
2. Operator Overloading
3. overload new operator

#include <iostream>
#include <cstdlib>
#include <new>
using namespace std;
   
class loc {
int longitude, latitude;
public:
  loc() {}
  loc(int lg, int lt) {
    longitude = lg;
    latitude = lt;
  }
   
  void show() {
    cout << longitude << " ";
    cout << latitude << "\n";
  }
};
   
// Global new
void *operator new(size_t size)
{
  void *p;
   
  p =  malloc(size);
  if(!p) {
    bad_alloc ba;
    throw ba;
  }
  return p;
}
   
// Global delete
void operator delete(void *p)
{
  free(p);
}
   
int main()
{
  loc *p1, *p2;
  float *f;
   
  try {
    p1 = new loc (10, 20);
  } catch (bad_alloc xa) {
    cout << "Allocation error for p1.\n";
    return 1;;
  }
   
  try {
    p2 = new loc (-10, -20);
  } catch (bad_alloc xa) {
    cout << "Allocation error for p2.\n";
    return 1;;
  }
   
  try {
    f = new float; // uses overloaded new, too
  } catch (bad_alloc xa) {
    cout << "Allocation error for f.\n";
    return 1;;
  }
   
  *f = 10.10F;
  cout << *f << "\n";
   
  p1->show();
  p2->show();
   
  delete p1;
  delete p2;
  delete f;
   
  return 0;
}