PPWIZARD is a free preprocessor for HTML, REXX, Visual Basic or any text files.
#ifdef |
A #ifdef command (like #if and #ifndef) can be used to conditionally include lines of text, this can be any other type of line or command except #elseif or #endif.
#if commands can be nested to any level and there need not be any lines between a #if command and a #endif or #elseif command.
Note that this command only checks on a single variable, for more complex requirements you will need to use a #if command along with calls to the Defined() routine. For performance reasons it is recommended that you use #ifdef and #ifndef commands where possible.
A common use of this command is as a method of creating block comments. Simply specify a variable you know does not exist!
Syntax |
[WhiteSpace]#ifdef MacroName
The "MacroName" specifies the name of a macro that should exist for the test to evaluate to true.
Example #1 |
#define Fred FredsValue #ifdef Fred ... #endif
Example #2 - Block Comment |
#ifdef DoesNotExist <P>This paragraph has been commented out as we are testing for a variable we know does not exist. #endif