Virtual Default Destructors in C++

Question

I\'ve got a large set of inherited classes (criteria) which inherit from a base class (criterion). Here\'s criterion\'s code

class criterion
{
p         


        

Answer 1

The recommendation is to insert:

virtual ~criterion() {}

Starting from C++11, you can use = default; instead of an empty body {}.

This is to avoid problems with deleting from a base class' pointer. Otherwise you will leak memory as derived classes' destructors will not be called.

criterion *c = new fastFilter();
delete c; // leaks