Preparing your code

The C++ and C Standard Libraries have a wide range of functions that allow you to apply tracing and reporting functions so that you can test if code is handling data in expected ways. Much of these facilities use conditional compilation so that the reporting only occurs in debug builds, but if you provide the traces with meaningful messages they will form part of the documentation of your code. Before you can report on the behavior of your code, you first have to know what to expect from it.

Invariants and conditions

Class invariants are conditions, the object state, that you know remain true. During a method call the object state will change, possibly to something that invalidates the object, but once...