Void - Revision history

Lou Montana: Some wiki formatting

2022-09-15T21:30:58Z

Some wiki formatting

← Older revision		Revision as of 23:30, 15 September 2022
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	{{TOC\|side}}		{{TOC\|side}}
	A variable of type '''Void''' is an '''undefined variable'''.		A [[Variables\|variable]] of type '''Void''' is an '''undefined variable'''.


	== Undefining Variables ==		== Undefining Variables ==

	~~You can use~~ [[nil]] to undefine variables.		[[nil]] can be used to undefine variables.

	<sqf>		<sqf>
Line 12:		Line 13:
	// myVar is undefined		// myVar is undefined
	</sqf>		</sqf>


			== String Representation ==

			The [[String]] representation of an undefined variable depends on its {{Link\|#Type Inference\|inferred type}}:

			{\| class="wikitable"
			! [[Data Types\|Data Type]]
			! [[String]]
			\|-
			\| [[Anything]]
			\|
			[[scalar bool array string 0xfcffffef]] ({{Name\|ofp\|short}})<br>
			[[scalar bool array string 0xe0ffffef]] ({{Name\|arma1\|short}})
			\|-
			\| [[Nothing]]
			\| scalar bool array string nothing 0xfcffffef
			\|-
			\| [[Number]]
			\| scalar
			\|-
			\| [[Boolean]]
			\| bool
			\|-
			\| [[Array]]
			\| array
			\|}


	== Comparisons ==		== Comparisons ==

	No comparison with variables ~~of this type~~ will work.		No comparison with any variables will work.

	'''Example:'''		'''Example:'''

	<sqf>		<sqf>
	// error		// error
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			== Detect an Undefined Variable ==

	In {{~~ofp~~}}, a ~~Variable becomes '''undefined''' when it is assigned to an undefined value,~~ or ~~an expression which refers to an undefined value somewhere.~~		The [[isNil]] command, introduced in {{arma1}}, allows to detect if a variable exists or not:
			<sqf>
			HelloThere = 42;
			isNil "HelloThere"; // false

	=~~= Names ==~~		HelloThere = nil;
			isNil "HelloThere"; // true
			</sqf>

	~~The [[String]] representation of an undefined variable is one of the following:~~		{{ArgTitle\|3\|isNil Workaround 1\|{{GVI\|ofp\|1.00}}}}

	[[~~Anything~~]]: ~~[[scalar bool array string 0xfcffffef]] ({{Name\|ofp\|short}})~~		[[SQS Syntax]]:
			<sqs>
	[~~[Anything~~]~~]: [~~[~~scalar bool array string 0xe0ffffef~~]~~] ({{Name\|arma1\|short}}~~)		_nil = format ["%1", _undefinedVariable]
			? (format ["%1", variableToTest] == _nil) : hint "variableToTest is nil"
	[[~~Nothing~~]]: ~~scalar bool array string nothing 0xfcffffef~~		</sqs>
			[[SQF Syntax]]:
	[~~[Number]~~]~~: scalar~~		<sqf>
			_nil = format ["%1", _undefinedVariable];
	[~~[Boolean~~]~~]: bool~~		if (format ["%1", variableToTest] == _nil) then { hint "variableToTest is nil" };
			</sqf>
	~~[[Array]]: array~~

	~~'''Caution: the string specification of the undefined variables is undocumented, and it is very likely to change in future version of the scripting language~~.~~'''~~		{{ArgTitle\|3\|isNil Workaround 2\|{{GVI\|ofp\|1.00}}}}

	~~The reliable way to check if the variable is~~ undefined ~~is that it silently fails any expression evaluations on it~~.		{{Feature\|obsolete\|{{arma1}} introduced [[isNil]], and {{arma2}} forbade undefined variables usage in script - see {{Link\|ArmA: Editing#Forward Compatibility}}.\|arma1}}

	~~'''Example'''~~:		The alternative way to check if a variable is undefined before [[isNil]] existence is that it silently fails any expression evaluations on it:
	<sqf>		<sqf>
	defined=false;if var==var then {defined=true};if var!=var then {defined=true};		defined = false;
	if !defined then {/we know it is undefined here/}		if (var == var) then
			{
			defined = true;
			};
			if (var != var) then
			{
			defined = true;
			};
			if (!defined) then
			{
			// we know var is undefined here
			};
	</sqf>		</sqf>

	~~The code above should not work in {{GameCategory\|arma2\|link=y}}, as stated [[ArmA: Editing#Forward Compatility\|here]].~~

	~~In {{Name\|arma1\|short}} or later [[isNil]] is the preferred way to check for this, like~~
	~~<sqf>isNil "varName";</sqf>~~

	== Type Inference ==		== Type Inference ==

	Suppose the variable '''a''' is undefined, and we set the variable '''b''' like so:~~<br>~~		Suppose the variable '''a''' is undefined, and we set the variable '''b''' like so:
	<sqf>b = a + [];</sqf>		<sqf>b = a + [];</sqf>

	The inferred type of b is now array - since b was the product result of an array [[+\|add]] operation with a definite array ([]) and an unknown type (a)		The inferred type of b is now array - since b was the product result of an array [[+\|add]] operation with a definite array ([]) and an unknown type (a)

	'''b''''s string representation will now be 'array', and b wil be considered an undefined array.		'''b'''<nowiki/>'s string representation will now be "array", and b wil be considered an undefined array.


	[[Category: Magic Types]]		[[Category: Magic Types]]

Lou Montana: Some wiki formatting

2022-07-22T15:23:01Z

Some wiki formatting

← Older revision		Revision as of 17:23, 22 July 2022
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			{{TOC\|side}}
	A variable of type '''Void''' is an '''undefined variable'''.		A variable of type '''Void''' is an '''undefined variable'''.

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	You can use [[nil]] to undefine variables.		You can use [[nil]] to undefine variables.

	myVar = 1;		<sqf>
	...		myVar = 1;
	myVar = nil;		// ...
			myVar = nil;
	~~myVar =~~> ~~undefined~~		// myVar is undefined
			</sqf>

	== Comparisons ==		== Comparisons ==
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	'''Example:'''		'''Example:'''

	// error		<sqf>
	[[if]] (undefinedVar == ...) [[then]] ...		// error
			if (undefinedVar == definedVar) then { /* ... */ };
			</sqf>
			<sqf>
			// error
			if (undefinedVar == undefinedVar) then { /* ... */ };
			</sqf>

	~~// error~~
	~~[[if]] (undefinedVar == undefinedVar) [[then]] ...~~


			In {{ofp}}, a Variable becomes '''undefined''' when it is assigned to an undefined value, or an expression which refers to an undefined value somewhere.
	In ~~Operation Flashpoint~~, a Variable becomes '''undefined''' when it is assigned to an undefined value, or an expression which refers to an undefined value somewhere.

	== Names ==		== Names ==
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	The [[String]] representation of an undefined variable is one of the following:		The [[String]] representation of an undefined variable is one of the following:

	[[Anything]]: scalar bool array string 0xfcffffef (~~OFP~~)		[[Anything]]: [[scalar bool array string 0xfcffffef]] ({{Name\|ofp\|short}})

	[[Anything]]: scalar bool array string 0xe0ffffef (~~ArmA~~)		[[Anything]]: [[scalar bool array string 0xe0ffffef]] ({{Name\|arma1\|short}})

	[[Nothing]]: scalar bool array string nothing 0xfcffffef~~<br>~~		[[Nothing]]: scalar bool array string nothing 0xfcffffef

	[[Number]]: scalar		[[Number]]: scalar
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	'''Example''':		'''Example''':
			<sqf>
			defined=false;if var==var then {defined=true};if var!=var then {defined=true};
			if !defined then {/we know it is undefined here/}
			</sqf>

	~~defined=false;if var==var then~~ {~~defined~~=~~true~~}~~;if var!=var then {defined=true~~};		The code above should not work in {{GameCategory\|arma2\|link=y}}, as stated [[ArmA: Editing#Forward Compatility\|here]].
	~~if !defined then {/we know it is undefined~~ here/}

	~~The code above should not work in [[:Category:Arma 2\|~~{{~~arma2~~}}~~]], as stated [[ArmA:_Editing#Forward_Compatility\|here]].~~		In {{Name\|arma1\|short}} or later [[isNil]] is the preferred way to check for this, like
			<sqf>isNil "varName";</sqf>
	~~In Armed Assault~~ or later [[isNil]] is the preferred way to check for this, like
	~~'''~~isNil~~'''~~ "varName"

	== Type Inference ==		== Type Inference ==

	Suppose the variable '''a''' is undefined, and we set the variable '''b''' like so:<br>		Suppose the variable '''a''' is undefined, and we set the variable '''b''' like so:<br>
	b = a + []		<sqf>b = a + [];</sqf>

	The inferred type of b is now array - since b was the product result of an array [[~~a plus b~~\|add]] operation with a definite array ([]) and an unknown type (a)		The inferred type of b is now array - since b was the product result of an array [[+\|add]] operation with a definite array ([]) and an unknown type (a)

	'''b''''s string representation will now be 'array', and b wil be considered an undefined array.		'''b''''s string representation will now be 'array', and b wil be considered an undefined array.


	[[Category: Magic Types]]		[[Category: Magic Types]]

Lou Montana: Text replacement - "{{arma2}}" to "{{arma2}}"

2021-07-20T00:52:36Z

Text replacement - "[[{{arma2}}]]" to "{{arma2}}"

← Older revision		Revision as of 02:52, 20 July 2021
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	if !defined then {/we know it is undefined here/}		if !defined then {/we know it is undefined here/}

	The code above should not work in [[{{arma2}}]], as stated [[ArmA:_Editing#Forward_Compatility\|here]].		The code above should not work in [[:Category:Arma 2\|{{arma2}}]], as stated [[ArmA:_Editing#Forward_Compatility\|here]].

	In Armed Assault or later [[isNil]] is the preferred way to check for this, like		In Armed Assault or later [[isNil]] is the preferred way to check for this, like

R3vo: category

2021-02-10T12:49:59Z

Lou Montana: Text replacement - " (={2,})([^ = ])(.)([^ = ])(={2,}) " to " $1 $2$3$4 $5 "

2021-01-31T18:05:07Z

Text replacement - " (={2,})([^ = ])(.*)([^ = ])(={2,}) * " to " $1 $2$3$4 $5 "

← Older revision		Revision as of 20:05, 31 January 2021
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	In Operation Flashpoint, a Variable becomes '''undefined''' when it is assigned to an undefined value, or an expression which refers to an undefined value somewhere.		In Operation Flashpoint, a Variable becomes '''undefined''' when it is assigned to an undefined value, or an expression which refers to an undefined value somewhere.

	==Names==		== Names ==

	The [[String]] representation of an undefined variable is one of the following:		The [[String]] representation of an undefined variable is one of the following:
Line 57:		Line 57:
	'''isNil''' "varName"		'''isNil''' "varName"

	==Type Inference==		== Type Inference ==

	Suppose the variable '''a''' is undefined, and we set the variable '''b''' like so:<br>		Suppose the variable '''a''' is undefined, and we set the variable '''b''' like so:<br>

Lou Montana: Text replacement - "ArmA 2" to "{{arma2}}"

2020-02-19T22:20:51Z

Text replacement - "ArmA 2" to "[[{{arma2}}]]"

← Older revision		Revision as of 00:20, 20 February 2020
Line 52:		Line 52:
	if !defined then {/we know it is undefined here/}		if !defined then {/we know it is undefined here/}

	The code above should not work in [[~~ArmA 2~~]], as stated [[ArmA:_Editing#Forward_Compatility\|here]].		The code above should not work in [[{{arma2}}]], as stated [[ArmA:_Editing#Forward_Compatility\|here]].

	In Armed Assault or later [[isNil]] is the preferred way to check for this, like		In Armed Assault or later [[isNil]] is the preferred way to check for this, like

Alef: /* ArmA 2 forward compatibility advise */

2008-04-15T11:48:27Z

ArmA 2 forward compatibility advise

← Older revision		Revision as of 13:48, 15 April 2008
Line 51:		Line 51:
	defined=false;if var==var then {defined=true};if var!=var then {defined=true};		defined=false;if var==var then {defined=true};if var!=var then {defined=true};
	if !defined then {/we know it is undefined here/}		if !defined then {/we know it is undefined here/}

			The code above should not work in [[ArmA 2]], as stated [[ArmA:_Editing#Forward_Compatility\|here]].

	In Armed Assault or later [[isNil]] is the preferred way to check for this, like		In Armed Assault or later [[isNil]] is the preferred way to check for this, like

Suma: /* Names */ Merged in string values.

2007-09-07T09:12:52Z

Names: Merged in string values.

← Older revision		Revision as of 11:12, 7 September 2007
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	The [[String]] representation of an undefined variable is one of the following:		The [[String]] representation of an undefined variable is one of the following:

	[[Anything]]: scalar bool array string 0xfcffffef~~<br>~~		[[Anything]]: scalar bool array string 0xfcffffef (OFP)

			[[Anything]]: scalar bool array string 0xe0ffffef (ArmA)

	[[Nothing]]: scalar bool array string nothing 0xfcffffef<br>		[[Nothing]]: scalar bool array string nothing 0xfcffffef<br>
	[[Number]]: scalar~~<br>~~
	[[Boolean]]: bool~~<br>~~		[[Number]]: scalar
	[[Array]]: array~~<br>~~
			[[Boolean]]: bool

			[[Array]]: array

	'''Caution: the string specification of the undefined variables is undocumented, and it is very likely to change in future version of the scripting language.'''		'''Caution: the string specification of the undefined variables is undocumented, and it is very likely to change in future version of the scripting language.'''

Suma: String values desribed below

2007-09-07T09:11:35Z

String values desribed below

← Older revision		Revision as of 11:11, 7 September 2007
Line 1:		Line 1:
	A variable of type '''Void''' is an '''undefined variable'''. When converted to a string with [[str]] or [[format]], this variable will always return [[scalar bool array string 0xe0ffffef]] (in [[Armed Assault]]) or [[scalar bool array string 0xfcffffef]] (in [[Operation Flashpoint]]).		A variable of type '''Void''' is an '''undefined variable'''.

	== Undefining Variables ==		== Undefining Variables ==

Suma: /* Names */ isNil

2007-09-07T09:10:50Z

Names: isNil

← Older revision		Revision as of 11:10, 7 September 2007
Line 45:		Line 45:
	defined=false;if var==var then {defined=true};if var!=var then {defined=true};		defined=false;if var==var then {defined=true};if var!=var then {defined=true};
	if !defined then {/we know it is undefined here/}		if !defined then {/we know it is undefined here/}

			In Armed Assault or later [[isNil]] is the preferred way to check for this, like
			'''isNil''' "varName"

	==Type Inference==		==Type Inference==

← Older revision		Revision as of 14:49, 10 February 2021
Line 65:		Line 65:

	'''b''''s string representation will now be 'array', and b wil be considered an undefined array.		'''b''''s string representation will now be 'array', and b wil be considered an undefined array.

	~~[[Category: Data Types]]~~

	[[Category: Magic Types]]		[[Category: Magic Types]]

Void - Revision history

Lou Montana: Some wiki formatting

Lou Montana: Some wiki formatting

Lou Montana: Text replacement - "{{arma2}}" to "{{arma2}}"

R3vo: category

Lou Montana: Text replacement - " (={2,})([^ = ])(.*)([^ = ])(={2,}) * " to " $1 $2$3$4 $5 "

Lou Montana: Text replacement - "ArmA 2" to "{{arma2}}"

Alef: /* ArmA 2 forward compatibility advise */

Suma: /* Names */ Merged in string values.

Suma: String values desribed below

Suma: /* Names */ isNil

Lou Montana: Text replacement - " (={2,})([^ = ])(.)([^ = ])(={2,}) " to " $1 $2$3$4 $5 "