isNil

1.00 1.00 1.50 1.00 0.50

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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.

This command does not exist in Operation Flashpoint/Arma: Cold War Assault but can be emulated (see Example 5).

Groups:

Variables

Syntax 1

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 or undefined

Syntax 2

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 - true if code returns Nothing, false otherwise

2.18

Syntax 3

Syntax:

namespace isNil variableName

Parameters:

namespace: Namespace, Object, Group, HashMap, 2.20 Control and Display

variableName: String

Return Value:

Boolean - true if variable is nil or undefined

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:

nil Variables Scheduler

Notes

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