Essential things to remember from today's class (class 4, 31st August)

Make sure that you could implement a basic vector class for yourself without
   reference to the in-class example.

How to define and use operators for your own classes.

How to make use of reference results.

How to split a program into a number of different files and compile and test
   them separately but combine them into a single executable.

The basics of defining templates, and why they don't go in .h files