Operators

Operators are the base commands each programming language is built on. They provide ability to perform basic mathematical and logical operations.

Requirements

To understand this article, you should read the following articles:

• Variables

Terms

Operand

An operand is any value given to an operator.

Expression

An expression is basically any code that returns a value. Read expression for more information.

Unary Operator

An unary operator is an operator that requires only one operand.

Unary operation:

operator expression

Binary Operator

A binary operator is an operator that requires two operands.

Binary operation:

expression operator expression

Operators

Assignment Operators

Assignment operators are used to assign values to a variable. OFP's scripting language provides only one assignment operator.

Assignment:

identifier = expression

Example 1:

a = b

You might think that this operator compares a and b, but that is not the case. = simply sets the left value to be the right one. Other assignment operators like +=, -= that can be found in other programming languages do not exist in SQF/SQS.

Example 2:

a = b * c

Arithmetic Operators

Remember arithmetic operations from school? These work just the same way. All operands of arithmetic operations must be Numbers. Arithmetic operations always return a Number.

Unary arithmetic operators (in order of precedence)

Operator	Name	Example
-	Negation	-a
+	Duplication	+a
(	Bracket	(expression)

Binary arithmetic operators

Operator	Name	Example
+	Addition	a + b
-	Subtraction	a - b
*	Multiplication	a * b
/	Division	a / b
%	Modulo	a % b
mod	Modulo	a mod b
^	Raise to the power of	a ^ b

ⓘ

See also Math Commands.

Logical Operators

Logical operators evaluate Boolean values. All operands of logical operations are Booleans. A logical operation always returns a Boolean.

Unary logical operators

Operator	Name	Example
!	Not	!a
not	Not	not a

The Not-operator always returns the inverse Boolean value. If a Boolean a is true, !a returns false and vice versa.

Binary logical operators

Operator	Name	Example
&&	And	a && b
and	And	a and b
||	Or	a || b
or	Or	a or b

• And only returns true if both operands are true
• Or returns true if one or both operands are true

There is no Xor, Nor and Nand operator. Those can be simulated using the basic operators though:

Combined logical operators

Name	Combination
Xor	((a || b) && !(a && b))
Nor	!(a || b)
Nand	!(a && b)

• Xor returns true if exactly one of both values is true
• Nor returns true if none of both values is true
• Nand returns true if not both values are true at the same time

Comparison Operators

Comparison operators compare two values. Operands of comparisons may be of type Number, Side, String, Object, Group, Structured Text, Config, Display or Control for == and !=, and Number for < > >= <=. Comparisons always return a Boolean: true if the comparison matches, false if not.

Comparison operators

Operator	Name	Example
==	Equal	a == b
!=	Not equal	a != b
<	Less than	a < b
>	Greater than	a > b
<=	Less or equal	a <= b
>=	Greater or equal	a >= b

ⓘ

invalid before Arma 3 v2.00	valid in all versions
a == true	a
a == false	!a

You could not compare Boolean values with == before Arma 3 v2.00 (in Arma 3 before that, use isEqualTo).
Comparing a Boolean value with true is the same as the value itself.
Comparing a Boolean value with false is the same as the inverse value.

Array Operators

The scripting language offers own operators to deal with arrays. All operands, of course, have to be of type Array. The return value of an array operation is an Array.

Unary array operators

Operator	Name	Example
+	Copy	+myArray

Normally arrays are assigned by reference. That means, if you assign array a to array b and change a afterwards, also b is changed. Use the copy operator to avoid this otherwise useful feature.

Example 1:

_arrayA = [1,2]; _arrayB = _arrayA; _arrayA set [0,5]; // _arrayA => [5,2] // _arrayB => [5,2]

Example 2:

_arrayA = [1,2]; _arrayB = +_arrayA; _arrayA set [0,5]; // _arrayA => [5,2] // _arrayB => [1,2]

Binary array operators

Operator	Name	Example
+	Concatenation	myArray1 + myArray2
-	Removal	myArray1 - myArray2

• + adds the second operand on the end of the first operand
• - removes all elements of the second operand from the first operand

Example 1:

_arrayA = [1,2]; _arrayB = [3,2,4]; _arrayC = _arrayA + _arrayB; // _arrayC => [1,2,3,2,4]

Example 2:

_arrayA = [1,2,3,2,4]; _arrayB = [2,3]; _arrayC = _arrayA - _arrayB; // _arrayC => [1,4]

String Operators

The scripting language offers one single string operator to concatenate strings. Both operands must be Strings. The return value of a string operation is a String.

Binary string operators

Operator	Name	Example
+	Concatenation	myString1 + myString2

• + adds the second operand on the end of the first operand

Example:

_stringA = "Hello "; _stringB = "World!"; _stringC = _stringA + _stringB; // _stringC => "Hello World!"

Config Operators

Config operators

Operator	Name	Example
+=	Append Array	myProperty[] += {element_1, element_2};

Example:

class B_Soldier_F;
class MySoldier: B_Soldier_F
{
	RespawnItems[] += {"FirstAidKit"}; //Adds additional FAK
};

/*
	Original RespawnItems[] array in config viewer:
	RespawnItems[] = {"FirstAidKit"};

	Modified RespawnItems[] array in config viewer:
	RespawnItems[] = {"FirstAidKit","FirstAidKit"};
*/

Order of Precedence

Order of operations, also called operator precedence, is a set of rules specifying which procedures should be performed first in a mathematical expression.

Precedence Overview

ⓘ

• Highest precedence means highest priority
• Associativity is (then) done from left to right, for example 3 + 5 + 8 will be processed as ((3 + 5) + 8)

Precedence	Type of Operator	Examples
11	Nular operators (commands with no arguments): commandName	Variables Values Braced expressions
10	Unary operators (commands with 1 argument): commandName a	+a -a +array ! b not b
9	Hash-select operator	array # index
8	Power operator	a ^ b
7	Number multiplication, division and remainder atan2 Config access (/)	a * b a / b a % b a mod b a / b a atan2 b
6	Number addition and subtraction Array addition and subtraction String addition min and max commands	a + b a - b arr1 + arr2 arr1 - arr2 str1 + str2 a min b a max b
5	else (if-then-else structure)	N/A
4	Binary operators (commands with 2 arguments): a commandName b	setDir switch colon (:)
3	== and != comparisons Number comparisons Config access (>>)	a == b a != b a > b a < b a >= b a <= b config >> name
2	Logical and operator	&& and
1	Logical or operator	|| or

Examples

Input	Process	Comment
1 + 2 * 3	1 + (2 * 3)	result equals 7, and not 9 (see also PEMDAS)
sleep 10 + random 20	(sleep 10) + random 20	sleep 10 will return Nothing, then + random 20 will be calculated but not used. sleep (10 + random 20) should be used instead

See Also

• SQF Syntax
• SQS Syntax