isNull

Global argument
Arma 3 v0.50
First in Operation Flashpoint v1.00

Command · Markdown · JSON · original wiki page

Description

Checks whether the tested item is null.
Which null type the item has to be equal to depends on the type of game entity tested:

Type	Object	Group	Control	Display	Location	Task	Script	Config	Diary Record	Team Member
Null value	objNull	grpNull	controlNull	displayNull	locationNull	taskNull	scriptNull	configNull	diaryRecordNull	teamMemberNull
Since	Operation Flashpoint v1.00		Armed Assault v1.00		Arma 2 v1.00		Arma 3 v1.30	Arma 3 v1.54	Arma 3 v2.00	Arma 3 v2.10

Important
A test via == does not work because a null value is not equal to anything, not even itself (configNull being the exception). See also isEqualTo.

Syntax

isNull entity

Parameters:

entity: Object, Control, Display, Group, Location, Task, Script Handle, Config, Diary Record or Team Member

Returns: Boolean

Examples

Example 1

if (isNil "obj") exitWith { hint "obj variable is undefined" };

if (isNull obj) then
{
    hint "obj variable is defined but is null";
}
else
{
    hint "obj variable is defined and is not null";
};

Example 2

Diary Record support before Arma 3 v2.00:

private _nullRecord = objNull createDiaryRecord []; // wrong parameters = failure to create a record = null value
private _createdRecord = player createDiaryRecord ["Diary", ["title", "description"]];
if (_createdRecord isEqualTo _nullRecord) then { hint "Failed" };

Team Member support before Arma 3 v2.10:

private _isNull = _teamMember isEqualTo teamMemberNull;