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documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

   ◄Directive Summary►  ◄Summary►  ◄IF Block Syntax►
──────────────────────────────────────────────────────────────────────────────
 
  Syntax:  IFDEF name
           IFNDEF name
 
  IFDEF causes assembly of a block of statements (see IF Block Syntax)
  if name is a previously defined symbol. IFNDEF causes assembly of a
  block of statements if name has not been defined.
 
  You can define symbols on the command line (or in Assembler Flags
  dialog box). Use of this feature with the IFDEF and IFNDEF directives
  lets you control which statements are assembled from the command line.
 
  ELSEIFDEF and ELSEIFNDEF correspond to IFDEF and IFNDEF.
 
  name    Any valid name. If it is a forward reference, it is undefined
          on Pass 1, but defined on Pass 2. This may cause conflicts
          with one-pass assembly.
 
  See Also: IF, IFE, IF1, IFB, IFDEF, IFDIF
                                    -♦-