Scripting: Operators – Arma Reforger

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Operators are elements used to generate operations between two values.

Contents


Precedence

Operators precedence (one having execution priority over another) in Enforce Script is identical to the C language:

Precedence Operator Description Associativity
1
++
 Postfix increment Left-to-right
--
 Postfix decrement
()
 Function call
[]
 Array subscripting
.
 Element selection by reference
2
++
 Prefix increment Right-to-left
--
 Prefix decrement
+
 Unary plus
-
 Unary minus
!
 Logical NOT
~
 Bitwise NOT
new
 Dynamic memory allocation
delete
 Dynamic memory deallocation
3
*
 Multiplication Left-to-right
/
 Division
%
 Modulo (remainder)
4
+
 Addition Left-to-right
-
 Subtraction
5
<<
 Bitwise left shift Left-to-right
>>
 Bitwise right shift
6
<
 Less than Left-to-right
<=
 Less than or equal to
>
 Greater than
>=
 Greater than or equal to
7
==
 Equal to Left-to-right
!=
 Not equal to
11
&
 Bitwise AND Left-to-right
12
^
 Bitwise XOR (exclusive or) Left-to-right
13
|
 Bitwise OR (inclusive or) Left-to-right
14
&&
 Logical AND Left-to-right
15
||
 Logical OR Left-to-right
8
=
 Direct assignment Right-to-left
+=
 Assignment by sum
-=
 Assignment by difference
*=
 Assignment by product
/=
 Assignment by quotient
%=
 Assignment by remainder
<<=
 Assignment by bitwise left shift
>>=
 Assignment by bitwise right shift
&=
 Assignment by bitwise AND
^=
 Assignment by bitwise XOR
|=
 Assignment by bitwise OR
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or see the Wikipedia article section.


Types

Assignment

=

The "assign operator sets the righthand value to the lefthand variable.

int five = 5;

⚠
This operator is NOT an equality check. For this, see ==.

++

The increment (or post-increment) operator adds 1 to the provided numerical variable. It only applies to int and float values.

int result = 5; result++; // result is 6

This operator can be used before the value as well (it is then called pre-increment operator):

int result = 5; ++result; // result is 6

The difference is that the returned value is incremented too:

int result = 5; Print(result++); // outputs 5, result is 6
int result = 5; Print(++result); // outputs 6, result is 6

--

The decrement (or post-decrement) operator removes 1 to the provided numerical variable. It only applies to int and float values.

int result = 5; result--; // result is 4

Same as ++, this operator can be used before the value (then called pre-decrement operator):

int result = 5; --result; // result is 4

int result = 5; Print(result--); // outputs 5, result is 4
int result = 5; Print(--result); // outputs 4, result is 4

+=

The "add to" operator adds the righthand value to the lefthand variable.

int result = 5; result += 3; // result is 8

-=

The "subtract from" operator subtract the righthand value to the lefthand variable.

int result = 5; result -= 3; // result is 2

*=

The "multiply with" operator multiplies the lefthand variable with the righthand value.

int result = 5; result *= 3; // result is 15

/=

The "divide by" operator multiplies the lefthand variable with the righthand value.

int result = 5; result /= 3; // result is 1 (floored int value)

Arithmetic

+

he "adds" operator does an addition between two numeric values, float and/or integer.

5 + 3; // result is 8 (int) 5 + 2.5; // result is 7.5 (float) 3.25 + 1.75; // result is 5.0 (float)

-

The "subtract from" operator does a subtraction between two numerical values, float and/or integer.

5 - 3; // result is 2 (int) 5 - 2.5; // result is 2.5 (float) 3.25 - 1.25; // result is 2.0 (float)

*

The multiplication sign does a multiplication between two numerical values, float and/or integer.

5 * 3; // result is 15 5 * 2.5; // result is 12.5 (float) 1.5 * 3.25; // result is 4.875 (float)

/

The "divided by" operator divides the left argument by the right one.
It can be applied to int, float or a mix of those. If both values are int, the return value will be a floored integer as well.

5 / 3; // result is 1 (int): 5/3 = 1.666(...), but integer floors the value 5 / 2.5; // result is 2.0 (float) 3.5 / 0.5; // result is 7.0 (float)

%

Modulo is an operator that gives the remainder of a division.
It only applies to integers.

ⓘ
See the Math.Repeat() method for a float modulo approximation.

5 % 3; // result is 2: 5 is one time 3, remaining 2 10 % 2; // result is 0: 10 is five times 2, remaining 0


Relational

>

The "greater than" operator returns true if the left argument is strictly greater than the right argument, false otherwise.
It can be applied to int, float or a mix of those.

10 > 11; // false 10 > 10; // false 10 > 9; // true 10 > 5; // true 10 > 5.5; // true 10.5 > 5; // true

<

The "lesser than" operator returns true if the left argument is strictly smaller than the right argument, false otherwise.
It can be applied to int, float or a mix of those.

10 < 11; // true 10 < 10; // false 10 < 9; // false 10 < 5; // false 10 < 5.5; // false 10.5 < 5; // false

>=

The "greater than or equal" operator returns true if the left argument is greater than or equal to the right argument, false otherwise.
It can be applied to int, float or a mix of those.

10 >= 11; // false 10 >= 10; // true 10 >= 9; // true 10 >= 5; // true 10 >= 5.5; // true 10.5 >= 5; // true

<=

The "lesser than or equal" operator returns true if the left argument is smaller than or equal to the right argument, false otherwise.
It can be applied to int, float or a mix of those.

10 <= 11; // true 10 <= 10; // true 10 <= 9; // false 10 <= 5; // false 10 <= 5.5; // false 10.5 <= 5; // false

==

The "equals" operator returns true if the left argument is strictly equal to the right argument, false otherwise.

Applies to:

  • bool
  • int
  • float
  • int / float, float / int
  • string (case-sensitive)
  • vector (value)
  • array (reference)
  • object (reference)

true == true; // true true == false; // false 10 == 11; // false 10 == 10; // true 10 == 9; // false 10 == 10.0; // true 10 == 10.1; // false MyClass object1 = new MyClass(); MyClass object2 = object1; object1 == object2; // true - same type, same instance MyClass object1 = new MyClass(); MyClass object2 = new MyClass(); object1 == object2; // false - same type, different instance

!=

The "different" operator returns true if the left argument is different from the right argument, false otherwise.

Applies to:

  • bool
  • int
  • float
  • int / float, float / int
  • string (case-sensitive)
  • vector (value)
  • array (reference)
  • object (reference)

10 != 11; // true 10 != 10; // false 10 != 9; // true 10 != 10.0; // false 10 != 10.1; // true MyClass object1 = new MyClass(); MyClass object2 = object1; object1 != object2; // false - same instance MyClass object1 = new MyClass(); MyClass object2 = new MyClass(); object1 != object2; // true - different instance

Logical

&&

The "and" operator returns true if both left and right conditions are true.

bool a = false; bool b = false; bool result = a && b; // result is false bool a = true; bool b = false; bool result = a && b; // result is false bool a = true; bool b = true; bool result = a && b; // result is true

||

The "or" logical operator returns true if left or right condition is true (or both).

bool a = false; bool b = false; bool result = a || b; // result is false bool a = true; bool b = false; bool result = a || b; // result is true bool a = true; bool b = true; bool result = a || b; // result is true

!

The "not" logical operator inverts a bool value: true becomes false and false becomes true.
It can also be used on:

  • int or float (0 comparison)
  • string (empty string comparison - usage of the string.IsEmpty() method is preferred)
  • object (null comparison)

bool a = true; bool result = !a; // result is false bool a = false; bool result = !a; // result is true bool isAlive = player.IsAlive(); bool isDead = !isAlive; int health = 0; if (!health) // same as if (health == 0) - not recommended Print("dead"); float fHealth = 0.0; if (!fHealth) // same as if (fHealth == 0) - not recommended Print("dead"); string data = ""; if (!data) // same as if (data.IsEmpty()) and if (data == "") - not recommended Print("empty string"); MyClass instance = null; if (!instance) // same as if (instance == null) Print("instance is null!"); // note that if (value) to check an object is -not- null works too if (instance) // same as if (instance != null) Print("instance is NOT null!");

Bitwise

&

The "bitwise AND" operator applies a AND operation between values bits - both bits must be 1 to return 1, otherwise 0 is returned.

int a = 13; // 00001101 in binary int b = 11; // 00001011 in binary int result = a & b; // 00001001 in binary // result is 9

|

The "bitwise OR" operator applies a OR operation between values bits - one of the bits must be 1 to return 1, otherwise 0 is returned.

int a = 13; // 00001101 in binary int b = 11; // 00001011 in binary int result = a | b; // 00001111 in binary // result is 15

~

The "bitwise NOT" operator reverts all bits of the provided value: 1 becomes 0 and vice-versa.

int a = 7; // 0000 0000 0000 0000 0000 0000 0000 0111 in binary (integer is 32 bits) int result = ~a; // 1111 1111 1111 1111 1111 1111 1111 1000 in binary // result is -8

<<

The left shift operator moves all bits of the provided value to the left.

int a = 1; // 00000001 in binary int result = a << 2; // shift 'a' bits 2 steps to the left // leftmost bits are pushed "out" // rightmost bits are filled with zeros // result is 00000100 // result is 4

>>

The right shift operator moves bits of the provided value to the right.

int a = 6; // 00000110 in binary int result = a >> 2; // shift 'a' bits 2 steps to the left // leftmost bits are filled with zeros // rightmost bits are pushed "out" // result is 00000001 // result is 1

String

+

The "adds" operator used with strings concatenates them. When it is used with string and another type, it will stringify (calling its .ToString() method) the other value. The left argument must be of string type for it to happen.

string a = "Hello"; string b = "there"; string result = a + b; // result is "Hellothere" string result = a + " " + b; // result is "Hello there" string stringifiedBool = "string " + true; // result is "string true" string stringifiedInt = "string " + 42; // result is "string 42" string stringifiedFloat = "string " + 4.0; // result is "string 4" string stringifiedFloat = "string " + 4.2; // result is "string 4.2" string stringifiedArray = "string " + myArray; // result is e.g "string 0x000002820B75EA68 {0,1,2,3,4}" string stringifiedVector = "string " + myVector; // result is e.g "string <0.000000, 0.500000, 1.000000>" string stringifiedEnum = "string " + MyEnum.B; // result is e.g "string 1" string stringifiedObject = "string " + myObject; // result is e.g "string MyClass<0x00000282360ECFD0>" string stringifiedTypename = "string " + MyClass; // result is e.g "string MyClass" string ok1 = "test" + 3; // will return "test3" string ok2 = "test" + 3 + true + false + 4; // will return "test3104" string error = 3 + "test"; // will throw a parsing error

Indexing

[]

The "get index" operator is used on arrays to get an element by its zero-based index (e.g 0 is first element, 1 is second, etc). It is very efficient on static arrays. It can also be used on strings, as strings are arrays of characters.

int staticNumbers[5] = { 1, 2, 3, 4, 5 }; int thirdStaticNumber = staticNumbers[2]; // result is 3, lightning fast on static arrays array<int> numbers = { 1, 2, 3, 4, 5 }; int thirdNumber = letters[2]; // result is 3 array<string> letters = { "A", "B", "C", "D", "E" }; string thirdLetter = letters[2]; // result is "C" string text = "ABCDE"; string thirdLetter = text[2]; // result is "C"

⚠
The [i] operator is equivalent to a .Get(i) method call for anything else than static arrays;

in order to save unrequired method calls, either use foreach or cache the call result whenever possible.

// bad for (int i, count = myArray.Count(); i < count; i++) { if (myArray[i].IsEmpty()) // .Get(i) equivalent Print("#" + i + " is empty"); else Print("trimmed '" + myArray[i] + "' is '" + myArray[i].Trim() + "'"); // .Get(i) equivalent, twice } // good for (int i, count = myArray.Count(); i < count; i++) { string value = myArray[i]; // .Get(i) equivalent if (value.IsEmpty()) Print("#" + i + " is empty"); else Print("trimmed '" + value + "' is '" + value.Trim() + "'"); } // best foreach (int i, string value : myArray) { if (value.IsEmpty()) Print("#" + i + " is empty"); else Print("trimmed '" + value + "' is '" + value.Trim() + "'"); }
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