C++ Formatting, File Organization, and Styles

Very extensive guide: Google's C++ Style Guide

C++ File Inclusion and Sharing

Header Guard Pattern

In order to prevent duplicate inclusions, it is recommended to adopt the "header guard pattern" (also called "define guard"). It looks something like this:

my_class.h:

#ifndef MY_CLASS
#define MY_CLASS
// ...
#endif // MY_CLASS

The comment at the end is not part of the macro, nor necessary, but is helpful as a reminder of "here is the end of our define block for {x}!"