PreProcessor Commands: Difference between revisions

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The PreProcessor and the Config Parser allow to use macros in configs. The purpose of macros is to re-use the same definition in scripts and configs multiple times. It also gives a centralized place to correct errors in this definition.
Know that edge cases may arise - see the collection of test-cases linked at the end of this page.
{{Feature | arma3 | In {{arma3}}, preprocessor commands are '''case-sensitive!'''}}


==Intro==


Preprocessor commands refer to the C(++) syntax used by the engine to, well, 'pre process' the text inside a config.cpp, mission.sqm, description.ext.
== Parsing ==


In fact, prepocess commands (can) apply to '''any''' ofp text file containing class statemens, since, these 'statements' are scrunched by the engine's internal C processor.
See {{HashLink|#Config Parser}} below:
* '''[[Config.cpp]]''' - parsed when PBO is binarized.
** [[localize]] cannot be used in macros, as it would hardcode string of current language instead of creating reference.
* '''[[Description.ext]]''' - parsed when mission is loaded or previewed in missions list.
* '''[[SQF Syntax|SQF]] script''' - parsed when [[preprocessFile]], [[preprocessFileLineNumbers]], [[compileScript]] or [[execVM]] is used.


The majority use however is in addons, and specifically, the config.cpp of the addon.


The two C, preprocessor commands recognised by the ofp engine are
== Macros ==


#include <filaname>
=== Comments ===
#define something as something else


===#include===
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.


Syntax
<syntaxhighlight lang="cpp">
// this is a single-line comment
/*
this is a
multi-line
comment
*/
myValue = something; //only this part of the line is commented out


#include <PathAndFileName> // '''note''' no semicolon
myArray = ["apple"/*, "banana"*/, "pear"]; // a portion in the middle of this line is commented out
#include "PathAndFileName" // mutually the same.
</syntaxhighlight>


The base purpose of this statement is to wedge in further statements into the current body of text. The reason for doing so, in ofp at least, is artistry. To break up one large confusing text many many pages long, into manageable chunks.
=== #define ===


The amount of 'chunks', ie, the number of included files, is solely dependent on how the author feels about it. In general, they will put similar elements together. All icons, all bulidings (versus trees) all cars (versus men) and so on. It is particularly common in vintage addons (people who have had some years in creating them) to put base charactersics of all the 'models' in one, base file, and then attach it to flavours of that base. Ie a base man with kahki trousers as standard included in files that change the trousers to pink, and so on. Ie, the base characterstics of the model, are NOT in the 'main' body of text as it's noisy and hardly worth looking at. A better example is one of weapons. Irrespective of the several addons made, they '''all''' include this one, weapon file, since they '''all''' will use AK47's with tangerine hand grenades with yellow spots. If some use M16's, no matter, you can be _certain_ an M16 is _also_ described in this base, weapon file, #included in all other files that need acces to M16's!
Using the ''#define'' instruction, it is possible to define a keyword and assign a definition to it. The keyword may contain any letter, digit or underscore in arbitrary order, as long as it does not start with a digit (RegEx: {{hl|[a-zA-Z_][0-9a-zA-Z_]*}}). As an example:
<syntaxhighlight lang="cpp">
#define true 1
</syntaxhighlight>


'''THE ENGINE DOES NOT CARE'''
The above means that whenever ''true'' is used in a config, the parser will replace this with the value ''1''.


From the perspective of the engine, it is of <u>no consequence</u>. Effectively the engine processes '''all''' files as '''one''' file. '''All''' of the chunks, all of the 'wedges', all of the #included files are merged into one, single file, for the purpose of compiling. Of a certainty, irrespective of how many #included files, you only get ONE, config.bin. (Config.bin, is the resultant output of all this processing)
The define-statement does swallow all spaces in between the macro-keyword and any non-space-character in the body (Note that tabs are not spaces! They don't get removed)
<syntaxhighlight lang="cpp">
#define MACRO                    test
MACRO // preprocesses to test (without any spaces)


#define MACRO test // There's a tab between MACRO and test
MACRO // preprocesses to " test" (without quotes - they are only used to show that the tab character didn't get removed)
</syntaxhighlight>


Processing continues at the <u>beginning of the included file</u> until it's EOF. At which point, processing continues at the statement after the initial #include.
The space between the macro-keyword and the body is also fully optional (though very useful to tell the preprocessor where the macro name ends and where the body begins):
<syntaxhighlight lang="cpp">
#define MACRO#test
MACRO // preprocesses to "test"
</syntaxhighlight>


Thus, anything required by that included file (if anything at all), must have 'appeared' _before_ the include statement.
==== Arguments ====
Arguments can be added to more complex macros, by including them between brackets after the keyword. For the name of the arguments the same rule as for the macro-keyword (see above) apply.
<syntaxhighlight lang="cpp">
#define CAR(NAME) displayName = NAME;
</syntaxhighlight>


It is quite common, for included files, to have, #include statement(s) of their own.
If ''CAR("Mini")'' is used, it will be replaced with ''displayName = "Mini";''. Multiple arguments can also be used:
<syntaxhighlight lang="cpp">
#define BLASTOFF(UNIT,RATE) UNIT setVelocity [0,0,RATE];
</syntaxhighlight>


Under this circumstance, processing continues at the beginning of _that_ included file, and so on.
Macro arguments may be composed of any characters, as long as they do not contain a comma (because commas are used as argument-delimiters). If quotes are being used, they have to be balanced. The same applies to single-quotes This is because String detection is working in macro arguments - Therefore commas can even get passed in as a macro argument as long as they are part of a String (This only works with Strings wrapped in double-quotes though). Note however that although the macro gets resolved properly, the comma gets removed from the String (probably a bug).
<syntaxhighlight lang="cpp">
#define MACRO(arg) arg
MACRO("Some, content") // preprocesses to "Some content" (note the missing comma)
</syntaxhighlight>


===PathName===
Quote escaping is also not supported in this context (neither with double- nor with single-quotes)
<syntaxhighlight lang="cpp">
#define MACRO(arg) arg
MACRO("Some ""content""") // preprocesses to "Some ""content"""
</syntaxhighlight>


Paths to Filenames in OFP do '''not''' follow convention, or in some cases, logic.
Passing arrays with more than one element {{hl|[el1,el2,...]}} as arguments into macros as well as any argument containing comas {{hl|"some, sentence"}}, will need a small workaround:
<syntaxhighlight lang="cpp">
#define HINTARG(ARG) hint ("Passed argument: " + str ARG)
</syntaxhighlight>


The following is <u>specific</u> to the #include statement as applied by the engine. Do ''not'' attempt to use the following when utilising other file references (such as icons or models eg)
Incorrect usage:
<syntaxhighlight lang="cpp">
HINTARG([1,2,3,4,5,6,7,8,9,0]); // ERROR, won't even compile
</syntaxhighlight>


#include "'''Any'''Addon\'''Any'''PathInTheAddon\SomeFile.SomeExtension"
Correct usage:
<syntaxhighlight lang="cpp">
#define array1 [1,2,3,4,5,6,7,8,9,0]
HINTARG(array1); // SUCCESS
</syntaxhighlight>


Take note that this is contrary to what you do with other file references.
The argument replacement is performed before the expansion of the macro body. That means one doesn't have to worry about name-conflicts between argument-names of the current macro and already defined macros:
<syntaxhighlight lang="cpp">
#define ONE foo
#define TWO(ONE) ONE
TWO(bar) // will preprocess to bar
</syntaxhighlight>


There is NO preceeding backslash.
==== Replacing parts of words ====
By default, only whole words can be replaced by arguments. If only a part of the word should be replaced, 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 &nbsp; (space).
<syntaxhighlight lang="cpp">
class NAME##_Button_Slider: RscText \
{ \
model = \OFP2\Structures\Various\##FOLDER##\##FOLDER; \
</syntaxhighlight>


Also note, that there is no default extension. It's called, whatever you want to call it (if anything at all)
It is also possible to use the single ''#'' to convert an argument to a string.
<syntaxhighlight lang="cpp">
statement = (this animate [#SEL, 0]); \
</syntaxhighlight>


==#define==
==== Multi-line ====
For longer definitions, one can stretch the macro across multiple lines. To create a multi-line definition, each line except the last one should end with a ''\'' character:
<syntaxhighlight lang="cpp">
#define DRAWBUTTON(NAME)\
__EXEC(idcNav = idcNav + 4) \
...
</syntaxhighlight>


For reasons lost in the mysts of Kernighan and Ritchie, this is referred to by the riduculous term 'macro'.
{{Feature | Informative | 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.}}


It is a 'macro' in the same way macros are used in Microsoft word, it can expand into a (very large) sequence of keystrokes.
=== #undef ===


For the sensibly minded you can effectively 'see' #defines as
Undefine (delete) a macro previously set by the use of #define.
<syntaxhighlight lang="cpp">
#undef NAME
</syntaxhighlight>


#define THIS = THAT
=== #if ===


#define true  1
'''Description:''' Checks condition and processes content if condition returns 1. Skips content if it returns 0
#define false 0
<syntaxhighlight lang="cpp">
#if __A3_DEBUG__ // Check if game is started in debug mode
#include "debug.hpp" // Include some file if debug mode is enabled
#endif
</syntaxhighlight>


For the non- sensibly minded and insane, you can indeed expand this 'macro'
=== #ifdef ===


#define ICONS(icn) icon=\SomeAddon\icons\##icn; /
A simple if-then construction to check whether a certain set of definitions has already been made:
                    model=\SomeAddon\##icn.p3d; /
<syntaxhighlight lang="cpp">
                    picture=\SomeAddon\##icn.paa
#ifdef NAME
 
...text that will be used if NAME is defined...
ICON(Peter);
#endif
ICON(Fred);
</syntaxhighlight>


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


icon=\SomeAddon\icons\Peter;
=== #ifndef ===
  ....
icon=\SomeAddon\icons\Fred;


The <u>purpose</u> of expanded macros (as illustrated above) is to reduce noise levels. To use a simple syntax to be legible, AND TO REDUCE TYPING. Reduction in typing means less typos.
Same as #ifdef, but checks for absence of definition instead.
<syntaxhighlight lang="cpp">
#ifndef NAME
...text that will be used if NAME ''isn't'' defined...
#endif
</syntaxhighlight>


The <u>purpose</u> of the first form of #define (as illustrated above) is to INCREASE typing but become more explicit, more legible.
=== #else ===


  motorcylce=false;
Provides alternative code to {{hl|#if}}, {{hl|#ifdef}}, {{hl|#ifndef}} checks.
<syntaxhighlight lang="cpp">
#ifndef NAME
...text that will be used if NAME is -not- defined...
#else
...text that will be used if NAME -is- defined...
#endif
</syntaxhighlight>
 
=== #endif ===
 
This ends a conditional block as shown in the descriptions of #ifdef and #ifndef above.
 
=== #include ===
 
Copies the code from a target file and pastes it where #include directive is.
<syntaxhighlight lang="cpp">
#include "file.hpp"
#include <file.txt> // Brackets are equivalent to quotation marks and may be used in their place.
</syntaxhighlight>
 
Source directory is:
* For any file without starting the include path with \ - the file's current directory
* When starting with \ - the internal filesystem root (see [[CMA:DevelopmentSetup#Addon_development|Addon Development]]) or the Game's working directory (only with [[Arma 3 Startup Parameters|-filePatching]] enabled)
 
A path beginning can be defined as follow:
* drive (only with [[Arma 3 Startup Parameters|-filePatching]] enabled): <syntaxhighlight lang="cpp">#include "D:\file.txt"</syntaxhighlight>
* PBO with [[PBOPREFIX]]: <syntaxhighlight lang="cpp"> #include "\myMod\myAddon\file.txt"</syntaxhighlight>
* 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):<!--
--><syntaxhighlight lang="cpp">#include"\myMod\myAddon\file.txt" // Arma 3\@myMod\addons\myAddon.pbo\file.txt;</syntaxhighlight>
 
To move to parent directory use '..' (two dots) (Supported since {{GVI|arma3|1.50}}):
<syntaxhighlight lang="cpp">
#include "..\file.sqf"
</syntaxhighlight>
 
Preprocessor does not support the use of macros for pre-defined file names.
<syntaxhighlight lang="cpp">
#define path "codestrip.txt"
#include path // this will cause an error
</syntaxhighlight>
 
=== # ===
 
'#' (single hash) operator wraps the text with quotation marks.
<syntaxhighlight lang="cpp">
#define STRINGIFY(s) #s
#define FOO 123
test1 = STRINGIFY(123); //test1 = "123";
test2 = STRINGIFY(FOO); //test2 = "123";
</syntaxhighlight>
 
This operator does only work on keywords following the rules for macro-names (see {{hl|#define}}-section). If one wants to stringify anything else (like e.g. a number), one has to use a stringify-macro that takes an argument and stringifies that (as in the example above).
<syntaxhighlight lang="cpp">
#define MACRO Test #123
MACRO // preprocesses to Test 123 - note that there are not any quotes inserted
</syntaxhighlight>
 
=== ## ===
 
'##' (double hash) operator concatenates what's before the ## with what's after it.
<syntaxhighlight lang="cpp">
#define GLUE(g1,g2) g1##g2
#define FOO 123
#define BAR 456
test1 = GLUE(123,456); //test1 = 123456;
test2 = GLUE(FOO,BAR); //test2 = 123456;
</syntaxhighlight>
 
=== __LINE__ ===
 
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.
 
=== __FILE__ ===
 
This keyword gets replaced with the CURRENT file being processed.
 
{{ArgTitle|3|__has_include|{{GVI|arma3|2.02}}}}
 
'''Description:''' Checks if given file exists. Returns 1 if it does, 0 if it does not exist.
#if __has_include("\z\ace\addons\main\script_component.hpp")
{{cc|File exists! Do something with it}}
#else
{{cc|File does not exist}}
  #endif
 
{{ArgTitle|3|__DATE_ARR__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Is replaced for current date in format [[Array|array]].
__DATE_ARR__ {{cc|2020,10,28,15,17,42}}
 
{{ArgTitle|3|__DATE_STR__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Is replaced for current date in format [[String|string]].
__DATE_STR__  {{cc|"2020/10/28, 15:17:42"}}
 
{{ArgTitle|3|__DATE_STR_ISO8601__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Is replaced for current date in format [[String|string]]. The date is presented in ISO8601 standard.
__DATE_STR_ISO8601__ {{cc|"2020-10-28T14:17:42Z"}}
 
{{ArgTitle|3|__TIME__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Is replaced for current time.
__TIME__ {{cc|15:17:42}}
 
{{ArgTitle|3|__TIME_UTC__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Is replaced for  UTC time.
__TIME_UTC__ {{cc|14:17:42}}
 
{{ArgTitle|3|__COUNTER__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Counts 1 up everytime it is defined.
__COUNTER__ {{cc|0}}
__COUNTER__ {{cc|1}}
__COUNTER__ {{cc|2}}
__COUNTER__ {{cc|3}}
__COUNTER_RESET__
__COUNTER__ {{cc|0}}
__COUNTER__ {{cc|1}}
__COUNTER__ {{cc|2}}
 
{{ArgTitle|3|__TIMESTAMP_UTC__|{{GVI|arma3|2.06}}}}
 
'''Description:''' Is replaced to the current timestamp in UNIX timestamp.
__TIMESTAMP_UTC__ {{cc|1622639059}}
 
{{ArgTitle|3|__COUNTER_RESET__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Resets counter. See example above.
 
{{ArgTitle|3|__RAND_INT{{hl|N}}__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Gets replaced by a random {{hl|N}} bit integer. {{hl|N}} can be 8, 16, 32 or 64, e.g:
<syntaxhighlight lang="cpp">
__RAND_INT8__
__RAND_INT16__
__RAND_INT32__
__RAND_INT64__
</syntaxhighlight>
 
__RAND_INT8__ {{cc|e.g -102}}
 
{{ArgTitle|3|__RAND_UINT{{hl|N}}__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Gets replaced by a random ''unsigned'' {{hl|N}} bit integer. {{hl|N}} can be 8, 16, 32 or 64, e.g:
<syntaxhighlight lang="cpp">
__RAND_UINT8__
__RAND_UINT16__
__RAND_UINT32__
__RAND_UINT64__
</syntaxhighlight>
 
__RAND_UINT8__ {{cc|108}}
 
{{ArgTitle|3|__GAME_VER__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Gets replaced by the game version.
__GAME_VER__ {{cc|02.00.146790}}
 
{{ArgTitle|3|__GAME_VER_MAJ__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Gets replaced by the ''major'' game version.
__GAME_VER_MAJ__ {{cc|02}}
 
{{ArgTitle|3|__GAME_VER_MIN__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Gets replaced by the ''minor'' game version.
__GAME_VER_MIN__ {{cc|00}}
 
{{ArgTitle|3|__GAME_BUILD__|{{GVI|arma3|2.02}}}}
 
'''Description:''' Gets replaced by the build number.
__GAME_BUILD__ {{cc|146790}}
 
{{ArgTitle|3|__ARMA__|{{GVI|arma3|2.02}}}}
 
'''Description:''' {{Wiki|stub}}
__ARMA__ {{cc|1}}
 
{{ArgTitle|3|__ARMA3__|{{GVI|arma3|2.02}}}}
 
'''Description:''' {{Wiki|stub}}
__ARMA3__ {{cc|1}}
 
{{ArgTitle|3|__A3_DEBUG__|{{GVI|arma3|2.02}}}}
 
'''Description:''' This macro is only set when the [[Arma 3 Startup Parameters| -debug parameter]] was provided. It can be used to switch mods or scripts to debug mode dynamically.
__A3_DEBUG__ {{cc|1 (If -debug was enabled)}}
 
 
== Config Parser ==
 
{{Feature|important|'''Config Parser''' keywords '''cannot''' be used in preprocessor {{HashLink|#Macros}}, e.g '''{{HashLink|##if}}'''!}}
 
=== __EXEC ===
 
This '''Config Parser''' macro allows to assign values to internal variables or just execute arbitrary code. The code inside {{hl|__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"; {{cc|6}}
_lev = [[parsingNamespace]] [[getVariable]] "lev"; {{cc|4}}
 
{{Feature | Warning |
{{hl|__EXEC}} doesn't like round brackets {{hl|()}} inside expressions. If grouping is needed, perhaps values could be calculated inside the brackets separately and assigned to local variables:
<code>__EXEC(a {{=}} (1+2);) {{cc|ERROR}}</code>
<div><code>__EXEC(_expr {{=}} 1+2;)
__EXEC(a {{=}} _expr;) {{cc|OK}}</code></div>
}}
 
=== __EVAL ===
 
With this '''Config Parser''' macro expressions can be evaluated, including previously assigned internal variables. Unlike {{hl|__EXEC}}, {{hl|__EVAL}} supports multiple parentheses:
 
w = __EVAL([[safeZoneW]] - (5 * ((1 / ([[getResolution]] [[select]] 2)) * 1.25 * 4)));
 
{{hl|__EVAL}} macros '''must''' be assigned to a config property and the expression '''must''' be terminated with {{hl|;}}. {{hl|__EVAL}} can only return [[Number]] or [[String]]: . Any other type is represented as [[String]], even [[Boolean]] type, which will result in either {{hl|"true"}} or {{hl|"false"}}.
 
{{Feature | Warning |
{{hl|__EVAL}} doesn't like curly brackets {{hl|{}}}; if code is needed in the expression, use [[compile]] [[String]] instead:
<code>result {{=}} __EVAL([[call]] {123}); {{cc|ERROR}}</code>
<code>result {{=}} __EVAL([[call]] [[compile]] "123"); {{cc|OK}}</code>}}
 
{{Feature|important|{{hl|__EXEC}} and {{hl|__EVAL}} macros are not suitable for SQF/SQS scripts but can be used in configs, including [[Description.ext|description.ext]]. <br>Both global and local variables set in {{hl|__EXEC}} are available in {{hl|__EVAL}}}}
 
 
== Errors ==
 
=== Error 2 ===
 
; Problem: Preprocessor failed error 2.
 
; How to fix: Add quotation marks in the title, or the file path. (''e.g.'' {{hl|#include "soGood.sqf"}}).
 
=== Error 6 ===
 
; Problem: Preprocessor failed on file X - error 6.
 
; Known reasons:
: "The problem is using {{hl|#ifdef #ifdef #endif #endif}}, a.k.a nested {{hl|#ifdef}}. This doesn't work in Arma. It's only possible to use {{hl|#ifdef}} and {{hl|#endif}} once and not nested."
: {{hl|#endif}} without preceding {{hl|#ifdef}} or {{hl|#ifndef}}
 
=== Error 7 ===
 
; Problem: Preprocessor failed on file X - error 7.
 
; Known reasons: The preprocessor encountered an unknown directive. Read, as a typo most has likely found a way into the file (something like {{hl|#inlcude}} or {{hl|#defien}}). Double-check all preprocessor directives in that file.
 
 
== External links ==
 
* [https://web.archive.org/web/20170319190732/http://ofp-faguss.com/files/ofp_preprocessor_explained.pdf {{ofp}} - Preprocessor Guide (Wayback Machine)]
* [https://github.com/Krzmbrzl/ArmaPreprocessorTestCases Collection of preprocessor test-cases]
 
 
[[Category:Scripting_Topics]]

Revision as of 10:21, 1 May 2022

The PreProcessor and the Config Parser allow to use macros in configs. The purpose of macros is to re-use the same definition in scripts and configs multiple times. It also gives a centralized place to correct errors in this definition. Know that edge cases may arise - see the collection of test-cases linked at the end of this page.

Arma 3
In Arma 3, preprocessor commands are case-sensitive!


Parsing

See Config Parser below:


Macros

Comments

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. 

// this is a single-line comment
 
/*
	this is a
	multi-line
	comment
*/
 
myValue = something; //only this part of the line is commented out

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

#define

Using the #define instruction, it is possible to define a keyword and assign a definition to it. The keyword may contain any letter, digit or underscore in arbitrary order, as long as it does not start with a digit (RegEx: [a-zA-Z_][0-9a-zA-Z_]*). 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.

The define-statement does swallow all spaces in between the macro-keyword and any non-space-character in the body (Note that tabs are not spaces! They don't get removed) 

#define MACRO                     test
MACRO // preprocesses to test (without any spaces)

#define MACRO	test // There's a tab between MACRO and test
MACRO // preprocesses to "	test" (without quotes - they are only used to show that the tab character didn't get removed)

The space between the macro-keyword and the body is also fully optional (though very useful to tell the preprocessor where the macro name ends and where the body begins): 

#define MACRO#test
MACRO // preprocesses to "test"

Arguments

Arguments can be added to more complex macros, by including them between brackets after the keyword. For the name of the arguments the same rule as for the macro-keyword (see above) apply. 

#define CAR(NAME) displayName = NAME;

If CAR("Mini") is used, it will be replaced with displayName = "Mini";. Multiple arguments can also be used: 

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

Macro arguments may be composed of any characters, as long as they do not contain a comma (because commas are used as argument-delimiters). If quotes are being used, they have to be balanced. The same applies to single-quotes This is because String detection is working in macro arguments - Therefore commas can even get passed in as a macro argument as long as they are part of a String (This only works with Strings wrapped in double-quotes though). Note however that although the macro gets resolved properly, the comma gets removed from the String (probably a bug). 

#define MACRO(arg) arg
MACRO("Some, content") // preprocesses to "Some content" (note the missing comma)

Quote escaping is also not supported in this context (neither with double- nor with single-quotes) 

#define MACRO(arg) arg
MACRO("Some ""content""") // preprocesses to "Some ""content"""

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] 
HINTARG(array1); // SUCCESS

The argument replacement is performed before the expansion of the macro body. That means one doesn't have to worry about name-conflicts between argument-names of the current macro and already defined macros: 

#define ONE foo
#define TWO(ONE) ONE
TWO(bar) // will preprocess to bar

Replacing parts of words

By default, only whole words can be replaced by arguments. If only a part of the word should be replaced, 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; \

It is also possible to use the single # to convert an argument to a string. 

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

Multi-line

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

#define DRAWBUTTON(NAME)\
	__EXEC(idcNav = idcNav + 4) \
	...
ⓘ
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.

#undef

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

#undef NAME

#if

Description: Checks condition and processes content if condition returns 1. Skips content if it returns 0 

#if __A3_DEBUG__ // Check if game is started in debug mode
#include "debug.hpp" // Include some file if debug mode is enabled
#endif

#ifdef

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...
#endif

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

#ifndef

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

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

#else

Provides alternative code to #if, #ifdef, #ifndef checks. 

#ifndef NAME
	...text that will be used if NAME is -not- defined...
#else
	...text that will be used if NAME -is- defined...
#endif

#endif

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

#include

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:

  • For any file without starting the include path with \ - the file's current directory
  • When starting with \ - the internal filesystem root (see Addon Development) or the Game's working directory (only with -filePatching enabled)

A path beginning can be defined as follow:

  • drive (only with -filePatching enabled): 
    #include "D:\file.txt"
  • PBO with PBOPREFIX: 
     #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 since Arma 3 logo black.png1.50): 

#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";

This operator does only work on keywords following the rules for macro-names (see #define-section). If one wants to stringify anything else (like e.g. a number), one has to use a stringify-macro that takes an argument and stringifies that (as in the example above). 

#define MACRO Test #123
MACRO // preprocesses to Test 123 - note that there are not any quotes inserted

##

'##' (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;

__LINE__

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.

__FILE__

This keyword gets replaced with the CURRENT file being processed.

__has_include

Description: Checks if given file exists. Returns 1 if it does, 0 if it does not exist. 

#if __has_include("\z\ace\addons\main\script_component.hpp")
// File exists! Do something with it
#else
// File does not exist
#endif

__DATE_ARR__

Description: Is replaced for current date in format array. 

__DATE_ARR__ // 2020,10,28,15,17,42

__DATE_STR__

Description: Is replaced for current date in format string. 

__DATE_STR__  // "2020/10/28, 15:17:42"

__DATE_STR_ISO8601__

Description: Is replaced for current date in format string. The date is presented in ISO8601 standard. 

__DATE_STR_ISO8601__ // "2020-10-28T14:17:42Z"

__TIME__

Description: Is replaced for current time. 

__TIME__ // 15:17:42

__TIME_UTC__

Description: Is replaced for UTC time. 

__TIME_UTC__ // 14:17:42

__COUNTER__

Description: Counts 1 up everytime it is defined. 

__COUNTER__ // 0
__COUNTER__ // 1
__COUNTER__ // 2
__COUNTER__ // 3
__COUNTER_RESET__
__COUNTER__ // 0
__COUNTER__ // 1
__COUNTER__ // 2

__TIMESTAMP_UTC__

Description: Is replaced to the current timestamp in UNIX timestamp. 

__TIMESTAMP_UTC__ // 1622639059

__COUNTER_RESET__

Description: Resets counter. See example above.

__RAND_INTN__

Description: Gets replaced by a random N bit integer. N can be 8, 16, 32 or 64, e.g: 

__RAND_INT8__
__RAND_INT16__
__RAND_INT32__
__RAND_INT64__

__RAND_INT8__ // e.g -102

__RAND_UINTN__

Description: Gets replaced by a random unsigned N bit integer. N can be 8, 16, 32 or 64, e.g: 

__RAND_UINT8__
__RAND_UINT16__
__RAND_UINT32__
__RAND_UINT64__

__RAND_UINT8__ // 108

__GAME_VER__

Description: Gets replaced by the game version. 

__GAME_VER__ // 02.00.146790

__GAME_VER_MAJ__

Description: Gets replaced by the major game version. 

__GAME_VER_MAJ__ // 02

__GAME_VER_MIN__

Description: Gets replaced by the minor game version. 

__GAME_VER_MIN__ // 00

__GAME_BUILD__

Description: Gets replaced by the build number. 

__GAME_BUILD__ // 146790

__ARMA__

Description:

This article is a Stub. You can help BI Community Wiki by expanding it.
__ARMA__ // 1

__ARMA3__

Description:

This article is a Stub. You can help BI Community Wiki by expanding it.
__ARMA3__ // 1

__A3_DEBUG__

Description: This macro is only set when the -debug parameter was provided. It can be used to switch mods or scripts to debug mode dynamically. 

__A3_DEBUG__ // 1 (If -debug was enabled)


Config Parser

⚠
Config Parser keywords cannot be used in preprocessor Macros, e.g #if!

__EXEC

This Config Parser macro allows 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
⚠
__EXEC doesn't like round brackets () inside expressions. If grouping is needed, perhaps values could be calculated inside the brackets separately and assigned to local variables:

__EXEC(a = (1+2);) // ERROR

__EXEC(_expr = 1+2;) __EXEC(a = _expr;) // OK

__EVAL

With this Config Parser macro expressions can be evaluated, including previously assigned internal variables. Unlike __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 only return Number or String: . Any other type is represented as String, even Boolean type, which will result in either "true" or "false".

⚠
__EVAL doesn't like curly brackets {}; if code is needed in the expression, use compile String instead:

result = __EVAL(call {123}); // ERROR

result = __EVAL(call compile "123"); // OK
⚠
__EXEC and __EVAL macros are not suitable for SQF/SQS scripts but can be used in configs, including description.ext.
Both global and local variables set in __EXEC are available in __EVAL


Errors

Error 2

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

Error 6

Problem
Preprocessor failed on file X - error 6.
Known reasons
"The problem is using #ifdef #ifdef #endif #endif, a.k.a nested #ifdef. 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

Problem
Preprocessor failed on file X - error 7.
Known reasons
The preprocessor encountered an unknown directive. Read, as a typo most has likely found a way into the file (something like #inlcude or #defien). Double-check all preprocessor directives in that file.


External links

Retrieved from "https://community.bistudio.com/wiki?title=PreProcessor_Commands&oldid=309092"