5.6 Booleans

Rules:

5.6.a. Boolean variables shall be declared as type bool.

5.6.b. Non-Boolean values shall be converted to Boolean via use of relational operators (e.g., < or !=), not via casts.

Example:

#include 
...

    bool b_in_motion = (0 != speed_in_mph);

Reasoning: The C90 standard did not define a data type for Boolean variables and C programmers have widely treated any non-zero integer value as true. The C99 language standard is backward compatible with this old style, but also introduced a new data type for Boolean variables along with new constants true and false in the stdbool.h header file.

Enforcement: These rules shall be enforced during code reviews.