C Language and Libraries Help (clang.hlp) (Table of Contents; Topic list)
Important Notice
The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.
defined
                                             ◄Up► ◄Contents► ◄Index► ◄Back►
─────C/C++ Language─────────────────────────────────────────────────────────
 
  Operator:  defined
 
  Syntax:    defined( identifier )
             !defined( identifier )
 
  Summary:   Used with the #if directive to test whether <identifier>
             is currently defined. Returns true (nonzero) if it is
             currently defined and returns false (0) if it is not. The
             logical NOT operator (!) can be used to reverse the logic
             of the defined operator. For example,
 
                  #if defined( __cplusplus )
                  #if defined( __cplusplus ) && !defined( M_I8086 )
 
  See also:  #define, #if, #ifdef, #ifndef, #undef
                                    -♦-