PreProcessor Commands

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Revision as of 16:42, 21 December 2018 by R3vo (talk | contribs) (added errors)
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The parser allows you to use macros in configs. Macros are a bit similar to functions in programming and allow you to use a single definition many times in the config, without having to duplicate the whole definition again and again. It also gives you a centralized place to correct errors in this definition. This page mainly refers to OFP, some examples won't work for ARMA and ARMA 2.




A comment is a line within code that is not actually processed by the game engine. They are used to make code more readable or to add notes for future reference. The preprocessor removes all comments from the file before it is processed. Therefore, comments are never actually "seen" by the game engine.

Comments may span multiple lines, or only part of a line if needed.

//this is a single-line comment

/* this is a
comment */

mycode = something; //only this part of the line is commented out

myArray = ["apple"/*,"bananna*/,"pear"]; //a portion in the middle of this line is commented out


Using the #define instruction, you can define a keyword and assign a definition to it. As an example:

  #define true 1

The above means that whenever true is used in a config, the parser will replace this with the value 1.


You can add arguments to more complex macros, by including them between brackets after the keyword:

  #define CAR(NAME) displayName = NAME;

If you now use CAR("Mini"), this will be replaced with displayName = "Mini";. Multiple arguments can also be used:

  #define BLASTOFF(UNIT,RATE) UNIT setVelocity [0,0,RATE];

Passing arrays with more than one element [el1,el2,...] as arguments into macros as well as any argument containing comas "some, sentence", will need a small workaround:

 #define HINTARG(ARG) hint ("Passed argument: " + str ARG)

Incorrect usage:

 HINTARG([1,2,3,4,5,6,7,8,9,0]); //ERROR, won't even compile

Correct usage:

 #define array1 [1,2,3,4,5,6,7,8,9,0] 

Replacing parts of words

By default you can only replace whole words by arguments. If you need to replace only part of a word, you can use the ## instruction. This is necessary when either the start or the end of the argument connects to another character that is not a ; (semi-colon) or   (space).

  class NAME##_Button_Slider: RscText \
  { \
     model = \OFP2\Structures\Various\##FOLDER##\##FOLDER; \

You can also use the single # to convert an argument to a string.

  statement = (this animate [#SEL, 0]); \


For longer definitions, you can stretch the macro across multiple lines. To create a multi-line definition, each line except the last one should end with a \ character:

     __EXEC(idcNav = idcNav + 4) \

NOTE: The backslash must be the last character in a line when defining a multi-line macro. Any character (including spaces) after the backslash will cause issues.


Undefine (delete) a macro previously set by the use of #define.

#undef NAME


You can use a simple if-then construction to check whether a certain set of definitions has already been made:

#ifdef NAME
  ...text that will be used if NAME is defined...

IFDEFs cannot be nested. The preprocessor will generate errors for all inner definitions if the outer definition doesn't exist.


Same as #ifdef, but checks for absence of definiton instead.

#ifndef NAME
  ...text that will be used if NAME isn't defined...


#ifndef NAME
  ...text that will be used if NAME isn't defined...
  ...text that will be used if NAME is defined...


This ends a conditional block as shown in the descriptions of #ifdef and #ifndef above.


Copies the code from a target file and pastes it where #include directive is.

#include "file.hpp"  
#include <file.txt> //Brackets are equivalent to quotation marks and may be used in their place.

Source directory is:

You can define a path beginning with:

#include "D:\file.txt"
#include "\myMod\myAddon\file.txt"
  • PBO (keep in mind that in this case, if the PBO's file name will be changed, all '#include' referencing it will need to be updated)
#include"\myMod\myAddon\file.txt" // Arma 3\@myMod\addons\myAddon.pbo\file.txt;

To move to parent directory use '..' (two dots) (Supported in Arma 3 since v1.49.131707):

#include "..\file.sqf"

Preprocessor does not support the use of macros for pre-defined file names.

#define path "codestrip.txt"
#include path //this will cause an error


'#' (single hash) operator wraps the text with quotation marks.

#define STRINGIFY(s) #s;
#define FOO 123
test1 = STRINGIFY(123); //test1 = "123";
test2 = STRINGIFY(FOO); //test2 = "123";


'##' (double hash) operator concatenates what's before the ## with what's after it.

#define GLUE(g1,g2) g1##g2
#define FOO 123
#define BAR 456
test1 = GLUE(123,456); //test1 = 123456;
test2 = GLUE(FOO,BAR); //test2 = 123456;


This config parser macro allows you to assign values to internal variables or just execute arbitrary code. The code inside __EXEC macros runs in parsingNamespace and variables defined in it will also be created in parsingNamespace. The variables can then be used to create more complex macros:

__EXEC(cat = 5 + 1;) __EXEC(lev = cat - 2;) _cat = parsingNamespace getVariable "cat"; //6 _lev = parsingNamespace getVariable "lev"; //4



With this config parser macro you can evaluate expressions, including previously assigned internal variables. Unlike with __EXEC, __EVAL supports multiple parentheses

w = __EVAL(safeZoneW - (5 * ((1 / (getResolution select 2)) * 1.25 * 4)));

__EVAL macros MUST be assigned to a config property and the expression MUST be terminated with ;. __EVAL can return only 2 types of data: Number and String. Any other type is represented as String, even Boolean type, which will result in either "true" or "false".



This keyword gets replaced with the line number in the file where it is found. For example, if __LINE__ is found on the 10th line of a file, the word __LINE__ will be replaced with the number 10.


This keyword gets replaced with the CURRENT file being processed.


Error 2

Preprocessor failed error 2.
How to fix
Add quotation marks in the title, or the file path. (e.g. #include "soGood.sqf").

Error 6

Preprocessor failed on file X - error 6.
Known reasons
  • "The problem is that I'm using #ifdef #ifdef #endif #endif. This doesn't work in Arma. It's only possible to use #ifdef and #endif once and not nested."
  • #endif without preceding #ifdef or ifndef

Error 7

Preprocessor failed on file X - error 7.
Known reasons
The preprocessor encountered an unknown directive. Read, you have probably a typo in the file (something like #inlcude or #defien). Double check all preprocessor directives in that file.

External links