C++ new[] into base class pointer crash on array access

Question

When I allocate a single object, this code works fine. When I try to add array syntax, it segfaults. Why is this? My goal here is to hide from the outside world the fact

Answer 1

Creating an array of 10 b's with new and then assigning its address to an a* is just asking for trouble.

Do not treat arrays polymorphically.

For more information see ARR39-CPP. Do not treat arrays polymorphically, at section 06. Arrays and the STL (ARR) of the CERT C++ Secure Coding Standard.