Prefer `underscore_style` names

Reason

The use of underscores to separate parts of a name is the original C and C++ style and used in the C++ Standard Library.

Note

This rule is a default to use only if you have a choice. Often, you don't have a choice and must follow an established style for consistency. The need for consistency beats personal taste.

This is a recommendation for when you have no constraints or better ideas. This rule was added after many requests for guidance.

Example

Stroustrup: ISO Standard, but with upper case used for your own types and concepts:

• int
• vector
• My_map

Enforcement

Impossible.