DelphiBasics
$IfOpt
Compiler Directive
Tests for the state of a Compiler directive
1   {$IfOpt Switch-}
    ...
  {$Else}
    ...
  {$EndIf}
2   {$IfOpt Switch+}
    ...
  {$Else}
    ...
  {$EndIf}
Description
The $IfOpt compiler directive is a meta-directive - it tests for the + or - state of a single character compiler directive.
 
For example:
 
{$IfOpt H+}
  ShowMessage('Longstrings are set on');
{$EndIf
}

 
It is useful to report on directive settings at the start of a program, when testing.
Notes
$IfOpt can be used multiple times in your code.
Related commands
$Define Defines a compiler directive symbol - as used by IfDef
$Else Starts the alternate section of an IfDef or IfNDef
$EndIf Terminates conditional code compilation
$IfDef Executes code if a conditional symbol has been defined
$IfNDef Executes code if a conditional symbol has not been defined
$UnDef Undefines a compiler directive symbol - as used by IfDef
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Example code : Show various default directive settings
begin
  // Show the default settings of various compiler directives
  {$IfOpt A+}
    ShowMessage('Align is On');
  {$Else}
    ShowMessage('Align is Off');
  {$EndIf}

  {$IfOpt B+}
    ShowMessage('BoolEval is On');
  {$Else}
    ShowMessage('BoolEval is Off');
  {$EndIf}

  {$IfOpt H+}
    ShowMessage('LongStrings is On');
  {$Else}
    ShowMessage('LongStrings is Off');
  {$EndIf}
end;
Show full unit code
   Align is Off
   BoolEval is Off
   LongStrings is On
 
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