| Description |
The $IfDef compiler directive starts a section of conditionally compiled code. Only if the specified Symbol has been defined.
Symbols come in two types. Predefined in Delphi, such as Console when running a console application. And defined by the $Define compiler direcctive.
$IfDef is very useful when developing code, allowing various sections to be compiled when testing.
|
|
| 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 |
| $IfNDef |
|
Executes code if a conditional symbol has not been defined |
| $IfOpt |
|
Tests for the state of a Compiler directive |
| $UnDef |
|
Undefines a compiler directive symbol - as used by IfDef |
|
|
|
| Example code : Setting up and using a test mode symbol |
var
text : string;
begin
// Set our code into test mode
{$Define TESTMODE}
text := 'We are in test mode';
// Display the value of text if we are in test mode
{$IfDef TESTMODE}
ShowMessage('text = '+text);
{$EndIf}
// Switch off test mode
{$UnDef TESTMODE}
// Display the value of text if we are in test mode
{$IfDef TESTMODE}
ShowMessage('text = '+text);
{$Else}
ShowMessage('Out of test mode now');
{$EndIf}
end;
|
| Show full unit code |
We are in test mode
Out of test mode now
|
|