Loop through pointer array returns wrong values

Question

I have a function that is returning a pointer to an array. If I try to access the returned pointer with something like array[5] it returns the correct value but if i try to loop over it then it returns random numbers. Why does it return different values when I loop over it but returns the correct ones when I specify the index?

int main()
{
    int *array = returnArray();

    for (size_t i = 0; i < 10; ++i)
    {
        cout << array[i] << endl;
    }

    return -1;
}

int *returnArray()
{
    int array2[10];
    int *ptr2;

    for (size_t i = 0; i < 10; ++i)
    {
        array2[i] = i;
    }

    ptr2 = array2;

    return ptr2;
}