c++ - overloaded new operator returning NULL memory for new object everytime -

i trying return null overloaded new operator function every time. here program

class xxx{       int n;       public:              void* operator new(size_t){                    cout<<"in operator new"<<endl;                    throw std::bad_alloc();                    //return (void *)null;         //line commented                    } }; int main(int argc,char *argv[]) {    xxx *x1=new xxx;    if(x1)       cout<<sizeof(x1);    else       cout<<"unable allocate memory"<<endl;    return 0; } 

here if use line return (void *)null; pointer x1 gets created not intended program.

and if use line throw std::bad_alloc();, program gets terminated/crashed instantly.

now want know if there way if can bypass "new operator" not allocate memory object.

this code works fine (tested msvc vs2010) , returns nullptr x allocation, requested in question:

#include <iostream> using namespace std;  class x { public:     x() { cout << "x::x()" << endl; }      static void* operator new(size_t size) {         return nullptr;     } };  int main() {     x* px = new x();     if (!px) {         cout << "allocation returned nullptr." << endl;     } else {         cout << "allocation succeeded." << endl;         delete px;         px = nullptr;     } } 

note in modern c++11, may want use nullptr instead of c++98/03 null.

note (void*) cast used in code useless.

moreover, if use throw std:bad_alloc(); inside custom implementation of new, program "crashes" beacuse throw exception never caught.
if insert try...catch(const std::exception&) block in main(), can make program exit in more "controlled" way (including printing error message).