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  ◄Compiler Directives► ◄Contents► ◄Index►                ◄Help on Help►
 
  Description
 
    Compiler directives are specialized comments that control the
    process of compiling source code. They begin with a dollar
    sign and a letter. For example, the range-checking directive
    looks like
 
       {$R+}
 
    A directive is not recognized if there are spaces or any other
    characters between the '{' and the '$'. For example, QuickPascal
    treats the following directive as a simple comment──range checking
    is not affected:
 
       { $R+}
 
    There are three categories of compiler directives:
 
      Category       Action
      ═══════════    ═══════════════════════════════════
      Switch         Turn a feature on or off
      Parameter      Control memory or use certain files
      Conditional    Compile a section of code
 
  Switch Directives
 
    A switch directive has a '+' or '-' after the directive letter.
 
      Switch    Scope    Default     Description
      ══════    ═════    ═══════     ════════════════════════════
      $A+│-     local       +        Align data
 
      $B+│-     local       -        Boolean, complete evaluation
 
      $D+│-     global      +        Debug information
 
      $F+│-     local       -        FAR calls
 
      $I+│-     local       +        I/O checking
 
      $L+│-     local       +        Local debug information
 
      $M+│-     local       +        Method call checking
 
      $N+│-     global      -        Numeric processing
 
      $R+│-     local       -        Range checking
 
      $S+│-     global      +        Stack checking
 
      $V+│-     local       +        VAR-string type checking
 
    Global control directives influence an entire program file. They
    must appear before the declaration portion of that file; that is,
    before the keywords USES, LABEL, CONST, TYPE, FUNCTION, PROCEDURE,
    or BEGIN.
 
    Local control directives influence the action of a localized
    section of code. They bracket the section of code that they
    control.
 
  Parameter-Accepting Directives
 
    Directive                    Description
    ═════════════════════════    ═════════════════════════
    $I <filename>                Includes a source file
    $L <filename>                Links an OBJ file
    $M <stack,minheap,maxheap>   Memory allocation control
 
  Conditional-Compilation Directives
 
    Directive                       Description
    ═══════════════                 ═════════════════════════════════
    $DEFINE <symbol>                Defines a symbol
    $UNDEF  <symbol>                Undefines a symbol
    $IFDEF  <symbol>                Tests if a symbol is defined
    $IFNDEF <symbol>                Tests if a symbol is undefined
    $IFOPT  <switch>                Tests if a switch is on or off
    $ELSE                           Marks the start of an alternate
                                    section
    $ENDIF                          Marks the end of a conditional
                                    section
 
    The action of conditional-compilation directives is similar to
    Pascal's IF statement. However, defined symbols are not available
    to a Pascal program. For example, the following code produces a
    compiler error:
 
       {$DEFINE debug}
              .
              .
       IF debug THEN
              .
              .