#ifdef, #ifndef, #if, #else, #elif, #endif

Overview

Used for conditional compiling using macros.
#if and #elif also support the following evaluation formulae.

Values (values that can be expressed as signed 32-bit integers. Behavior is undefined for other values).
The negative sign for a given value (addition and subtraction expressions not supported).
defined(macro name)
!defined(macro name)
Equality operators (==, !=)
Relational operators (<, <=, >, >=)
Bitwise AND (&&), bitwise OR (||)
Combinations of the above.

Errors are generated when undefined macros are used in evaluation formulae.

Code Example

#define USE_FUNCTION_A
#ifdef  USE_FUNCTION_A
    FunctionA:
        ...
#endif


#if (defined(AAA) && (BBB == 1))
    ...
#endif

Revision History

2011/12/20: Initial version.

CONFIDENTIAL