MISRA.ELIF.COND.NOT_BOOL.2012

#elif condition is not 0 or 1

MISRA C 2012 Rule 20.8: The controlling expression of a #if or #elif preprocessing directive shall evaluate to 0 or 1

Category: Required

Analysis: Decidable, Single Translation Unit

Applies to: C90, C99

Amplification

This rule does not apply to controlling expressions in preprocessing directives which are not evaluated. Controlling expressions are not evaluated if they are within code that is being excluded and cannot have an effect on whether code is excluded or not.

Rationale

Strong typing requires the controlling expression of conditional inclusion preprocessing directives to have a Boolean value.

Example

#define FALSE 0 
#define TRUE  1

#if FALSE            /* Compliant                              */ 
#endif

#if 10               /* Non-compliant                          */ 
#endif

#if ! defined ( X )  /* Compliant                              */ 
#endif

#if A > B            /* Compliant assuming A and B are numeric */ 
#endif

See also

Rule 14.1