

#if                  Preprocessing Directive                  #if




Include code conditionally


The preprocessing  directive #if  tells the preprocessor  that if
constant-expression is  true (i.e., that  it evalutes to  a value
other than zero), then include the following lines of code within
the  program until  it  reads the  next #elif,  #else, or  #endif
directive.

The constant-expression  must be  an integral expression,  and it
cannot include a sizeof  operator, a cast, or an enumeration con-
stant.  All macro  substitutions are performed upon the constant-
expression  before it  is evaluated.   All integer  constants are
treated as  long objects, and  are then evaluated.   If constant-
expression includes character constants, all escape sequences are
converted into characters before evaluation.

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

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




































COHERENT Lexicon                                           Page 1


