isNil

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Description

Description:
Tests whether a variable is nil or undefined from its identifier, or whether the given expression evaluates to nil or Nothing.
Operation Flashpoint
This command does not exist in Operation Flashpoint/Arma: Cold War Assault but can be emulated (see Example 5).
Groups:
Variables

Syntax

Syntax:
isNil variableName
Parameters:
variableName: String - missionNamespace's or local variable's identifier (e.g "globalVariable", "_localVariable")
Return Value:
Boolean - true if variable is nil

Alternative Syntax

Syntax:
isNil code
Parameters:
code: Code - code to evaluate:
  • the code will be executed; isNil { player setDamage 1 }; will kill the player
  • the code will not be allowed to suspend while expression is evaluated, even if the parent scope allows it (see Example 4).
Return Value:
Boolean - false if code returns Nothing, true otherwise

Examples

Example 1:
if (isNil "TAG_globalVariable") then { TAG_globalVariable = 0 }; if (isNil "_localVariable") then { hint "_localVariable is nil" };
Example 2:
isNil { player getVariable "someVar" };
Example 3:
_myArray = [0, 1]; isNil { _myArray select 0 }; // returns false isNil { _myArray select 1 }; // returns false isNil { _myArray select 2 }; // returns true isNil { _myArray select 3 }; // throws a script error. only length+1 select is allowed
Example 4:
This trick forces executing something in Unscheduled Environment:0 spawn { systemChat str canSuspend; // chat shows true isNil { hint str canSuspend }; // hint shows false };
Example 5:
Operation Flashpoint String comparison workaround: ; SQS Syntax _nil = format ["%1", _undefinedVariable] ? (format ["%1", variableToTest] == _nil) : hint "variableToTest is nil" // SQF Syntax _nil = format ["%1", _undefinedVariable]; if (format ["%1", variableToTest] == _nil) then { hint "variableToTest is nil" };

Additional Information

See also:
nilVariablesScheduler

Notes

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