Question

Suppose I have a class with overloaded operator new.

class Class {
public:
   void* operator new( size_t );
   void operator delete( void* );
};

Will objects of that class always be allocated with the overloaded operator new when I use new Class() or is it possible that the default operator new is used when new Class() construct appears in code?

Answer 1

The overloaded operator new and operator delete will always be used unless you explicitly do something like this:

// Allocate using global new.
MyClass* my_object = ::new MyClass();

// Use object normally.
my_object->my_method();

// Deallocate using global delete.
::delete my_object;

Or, as a somewhat extreme illustrative example, something like this:

#include <new>

// Use global placement new to allocate in a buffer created by global new.
MyClass* my_object = ::new(::operator new(sizeof(MyClass))) MyClass()

// Use object normally.
my_object->my_method();

// Explicitly invoke destructor.
my_object->~MyClass();

// Explicitly deallocate memory.
::operator delete(my_object);

Hope this helps.