Objective-C preprocessor directive for 'if not'

Question

I understand how to use a preprocessor directive like this:

#if SOME_VARIABLE     // Do something #else     // Do something else #endif 

But what if I only want to do something IF NOT SOME_VARIABLE.

Obviously I still could do this:

#if SOME_VARIABLE  #else     // Do something else #endif 

. . . leaving the if empty, But is there a way to do:

#if not SOME_VARIABLE    // Do something #endif 

Apple documentation here suggests not, but this seems like a very basic need.

Basically I want to do the preprocessor equivalent of:

if(!SOME_VARIABLE)( {    // Do Something } 

Answer 1

you could try:

#if !(SOME_VARIABLE)    // Do something #endif 

Answer 2

Are you trying to check if something is defined or not? If yes, you can try:

#ifndef SOME_VARIABLE

or

#if !defined(SOME_VARIABLE)