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)

Binary arithmetic operators

Note

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

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

Binary logical operators

• 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

• 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

Note

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

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

• + 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

• + 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

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

Note

• 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)

Examples

See Also

• SQF Syntax
• SQS Syntax