Deleting a derived class object using a pointer to a base class that has a non-virtual destructor results in undefined behavior. To correct this situation, the base class should be defined with a virtual destructor. For example, following program results in undefined behavior.
Although the output of following program may be different on different compilers, when compiled using Dev-CPP, it prints following:
Constructing base Constructing derived Destructing base
Making base class destructor virtual guarantees that the object of derived class is destructed properly, i.e., both base class and derived class destructors are called. For example,
Constructing base Constructing derived Destructing derived Destructing base
As a guideline, any time you have a virtual function in a class, you should immediately add a virtual destructor (even if it does nothing). This way, you ensure against any surprises later.