To help others navigate your existing code and use the APIs you provide, a good idea is to provide documentation generated from the comments in your code. There's no better place for such documentation than just right next to the functions and data types it describes, and this helps a lot in keeping them in sync.
A de facto standard tool for writing such documentation is Doxygen. Its positives are that it's fast (especially for big projects and HTML document generation), the generator has some built-in correctness checks (for example, for partially documented parameters in a function – a good marker to check whether the documentation is still up to date), and it allows the navigation of class and file hierarchies. Its disadvantages include not being able to do a full-text search, less than ideal PDF generation, and an interface some may find cumbersome.
Fortunately, the usability flaws can be remediated by using another popular...
