Do I need to nullify a member variable in the destructor?

Question

Why one would want to explicitly clear the a vector member variable (of on in a dtor (please see the code below). what are the benefits of clearing the vector, even though i

Answer 1

In the case of p_, there is no need to set it equal to null in the destructor, but it can be a useful defensive mechanism. Imagine a case where you have a bug and something still holds a pointer to a B object after it has been deleted:

If it trys to delete the B object, p_ being null will cause that second delete to be innocuous rather than a heap corruptor.

If it trys to call a method on the B object, p_ being null will cause a crash immediately. If p_ is still the old value, the results are undefined and it may be hard to track down the cause of the resulting crash.