Nạp chồng toán tử subscript [] trong C++

#include <iostream>
using namespace std;
const int SIZE = 15;
class ViDuMang
{
private:
    int mang[SIZE];
public:
    ViDuMang()
    {
        register int i;
        for (i = 0; i < SIZE; i++)
        {
            mang[i] = i;
        }
    }
    int& operator[](int i)
    {
        if (i > SIZE)
        {
            cout << "\n======================\n" << endl;
            cout << "Chi muc vuot gioi han!" << endl;
            // Tra ve phan tu dau tien.
            return mang[0];
        }
        return mang[i];
    }
};
int main()
{
    ViDuMang V;   cout << "Gia tri cua V[3] la: " << V[3] << endl;
    cout << "Gia tri cua V[6] la: " << V[6] << endl;
    cout << "Gia tri cua V[16] la: " << V[16] << endl;   return 0;
}