What is the purpose of the “final” keyword in C++11 for functions?

Question

What is the purpose of the final keyword in C++11 for functions? I understand it prevents function overriding by derived classes, but if this is the case, then

Answer 1

Final keyword in C++ when added to a function, prevents it from being overridden by a base class. Also when added to a class prevents inheritance of any type. Consider the following example which shows use of final specifier. This program fails in compilation.

#include 
using namespace std;

class Base
{
  public:
  virtual void myfun() final
  {
    cout << "myfun() in Base";
  }
};
class Derived : public Base
{
  void myfun()
  {
    cout << "myfun() in Derived\n";
  }
};

int main()
{
  Derived d;
  Base &b = d;
  b.myfun();
  return 0;
}

Also:

#include 
class Base final
{
};

class Derived : public Base
{
};

int main()
{
  Derived d;
  return 0;
}