Created an extended version of the standard string class that allows case-insensitive searching and comparison;

Learned how to use include guards to prevent a class interface from accidentally being defined more than once;

Learned more about the hazards of the “magic” value 0, as well as how we can prevent one of them that can occur when using the standard string class;

Learned how to restrict the application of a constructor via the explicit keyword.

Discovered just how difficult it is to anticipate how a program will be used and how many bugs it may contain;

Seen how a seemingly simple request for an added feature in a program can be extremely difficult to fulfill.