Is it valid to address one element beyond the end of an array?

Question

Can we increase the size during run time? What if, we exceed the size of array elements?

Answer 1

No for an array you can not go beyond the size of array as you may be entering into restricted area and may result in segmentation fault.

Only C99 allows to have the size of address at runtime, following code is perfectly valid with C99 but not with standard C

int main(int argc, char **argv)
{
    size_t size;
    cin >> size;
    int array[size];
    for(size_t i = 0; i < size; i++)
    {
        array[i] = i;
        cout << i << endl;
    }

    return 0;
}

If you want to increase the size of array at runtime using malloc/calloc (or new in case of C++) use the pointer instead (pointer can be used in a same way as array with the dynamic allocation).

Answer 2

Yes you can extend the size at run time, but if you will try to point an element outside of the array , it will show unexpected behavior and sometimes Index Outside error..