Question

Possible Duplicate:
How can I tell if an object is statically or dynamically allocated on the constructor?

struct Foo {
    Foo ();
};

int main ()
{
    Foo foo;                   // Case A
    Foo * p_foo = new Foo ();  // Case B
}

Foo :: Foo ()
{
    if (allocated_on_stack) {
        // Case A
    }
    if (allocated_on_heap) {
        // Case B
    }
}

Can Foo’s constructor distinguish these two cases?

Answer 1

The short answer to the question is no.

There are theoretical solutions, for instance you could replace new (on class or global level) and keep track of all new allocated pointers and compare to this list to your this pointer in the constructor.

struct Foo {
    Foo ()
    {
        //Check if `this` is in s_instances
    }
    void* operator new(size_t size)
    {
        void* pointer = ::new(size);
        s_instances.push_back(pointer);
        return pointer;
    }
    void operator delete (void* pointer)
    {
        //remove from s_instances and call global delete
    }
    static std::vector<void*> s_instances;
};

(This code won’t catch Foo allocated with new Foo[count])

Why do you need this though?