

#ifdef               Preprocessing Directive               #ifdef




Include code conditionally


The preprocessing directive  #ifdef checks whether identifier has
been defined as a macro  name.  If identifier has been defined as
a macro, then the preprocessor includes group within the program,
up to the next  #elif, #else, or #endif directive.  If identifier
has not been defined, however, then group is skipped.

An #ifdef directive can be followed by any number of #elif direc-
tives, by one #else directive,  and must be followed by an #endif
directive.

***** Example *****

For an example of using this directive in a program, see assert.

***** See Also *****

#elif, #else, #endif, #if, #ifndef, C preprocessor




































COHERENT Lexicon                                           Page 1


