Placement New and Virtual Functions

/*
    PROGRAM OUTPUT

Testing without vtable...

Size of object is 4
0
1
2
3
4
5
6
7
8
9

Testing with vtable...

Size of object is 8
0
1
2
3
4
5
6
7
8
9

*/


#include <stdlib.h>
#include <iostream>


#define ARRAY_SIZE 10


using namespace std;


class VRoot {


    public:


        virtual void PrintValue () = 0;


};


class VRootImplemented : public VRoot {


    private:


        int value;


    public:


        VRootImplemented (int value) {

            this->value=value;

        }


        void PrintValue () {

            cout << value << "\n";

        }

};


class NoVRoot {


    private:


        int value;


    public:


        NoVRoot (int value) {

            this->value=value;

        }


        void PrintValue () {

            cout << value << "\n";

        }


};


void main () {

    //  TEST 1
    cout << "Testing without vtable...\n\nSize of object is " << sizeof(NoVRoot) << "\n";

    //  Allocate array
    NoVRoot * p_no_v=(NoVRoot *)malloc(sizeof(NoVRoot)*ARRAY_SIZE);
    //  Theoretically check malloc success here

    //  Fill array
    for (int i=0;i<ARRAY_SIZE;++i) new (p_no_v+i) NoVRoot (i);

    //  Call PrintValue() on each item
    for (int i=0;i<ARRAY_SIZE;++i) p_no_v[i].PrintValue();

    //  Theoretically clean up here

    //  TEST 2
    cout << "\nTesting with vtable...\n\nSize of object is " << sizeof(VRootImplemented) << "\n";

    //  Allocate array
    VRootImplemented * p_v=(VRootImplemented *)malloc(sizeof(VRootImplemented)*ARRAY_SIZE);

    //  Fill array
    for (int i=0;i<ARRAY_SIZE;++i) new (p_v+i) VRootImplemented (i);

    //  Call PrintValue() on each item
    for (int i=0;i<ARRAY_SIZE;++i) {

        VRoot * test=&(p_v[i]);

        test->PrintValue();

    }

    //  Theoretically clean up here

}