Operators
An operator is a symbol for performing an operation or conditional evaluation on one or more values. Operators are used in Lua to manipulate data, perform arithmetic calculations, compare values, and control program flow. Understanding operators is essential for writing efficient and expressive Lua scripts in Highrise.
Logical Operators
Logical operators are used to perform logical operations on boolean values. Lua supports the following logical operators:
and
: Returnstrue
if both operands aretrue
.or
: Returnstrue
if at least one operand istrue
.not
: Returns the opposite boolean value of the operand.
Logical AND Operator (and
)
The logical AND operator (and
) returns true
if both operands are true
. Otherwise, it returns false
. Here's an example of using the logical AND operator in Lua:
local a = true
local b = false
print(a and b) --> false
print(a and true) --> true
In this example, the expression a and b
evaluates to false
because b
is false
. The expression a and true
evaluates to true
because both a
and true
are true
.
Logical OR Operator (or
)
The logical OR operator (or
) returns true
if at least one operand is true
. Otherwise, it returns false
. Here's an example of using the logical OR operator in Lua:
local a = true
local b = false
print(a or b) --> true
print(false or b) --> false
In this example, the expression a or b
evaluates to true
because a
is true
. The expression false or b
evaluates to false
because both operands are false
.
Logical NOT Operator (not
)
The logical NOT operator (not
) returns the opposite boolean value of the operand. If the operand is true
, it returns false
. If the operand is false
, it returns true
. Here's an example of using the logical NOT operator in Lua:
local a = true
local b = false
print(not a) --> false
print(not b) --> true
In this example, not a
evaluates to false
because a
is true
. not b
evaluates to true
because b
is false
.
Comparison Operators
In this table, a
and b
represent variables or values that are being compared.
Operator | Description | Example | Result |
---|---|---|---|
== | Equal to | a == b | true if a is equal to b , false otherwise |
~= | Not equal to | a ~= b | true if a is not equal to b , false otherwise |
< | Less than | a < b | true if a is less than b , false otherwise |
> | Greater than | a > b | true if a is greater than b , false otherwise |
<= | Less than or equal to | a <= b | true if a is less than or equal to b , false otherwise |
>= | Greater than or equal to | a >= b | true if a is greater than or equal to b , false otherwise |
Comparison Examples
In this table, a
and b
represent variables or values that are being compared.
Expression | Description | Result |
---|---|---|
5 == 5 | 5 is equal to 5 | true |
5 ~= 5 | 5 is not equal to 5 | false |
10 < 20 | 10 is less than 20 | true |
20 > 30 | 20 is greater than 30 | false |
15 <= 15 | 15 is less than or equal to 15 | true |
25 >= 30 | 25 is greater than or equal to 30 | false |
Arithmetic Operators
Arithmetic operators are used to perform mathematical calculations on numeric values. In this table, a
and b
represent variables or values that are being operated on.
Operator | Description | Example | Result |
---|---|---|---|
+ | Addition | a + b | Sum of a and b |
- | Subtraction | a - b | Difference between a and b |
* | Multiplication | a * b | Product of a and b |
/ | Division | a / b | Quotient of a divided by b |
% | Modulus | a % b | Remainder of a divided by b |
^ | Exponentiation | a ^ b | a raised to the power of b |
- | Negation | -a | Negative value of a |
// | Floor Division | a // b | Quotient of a divided by b , rounded down to the nearest integer |
Compound Assignment Operators
You can use compound assignment operators to combine an arithmetic operation with an assignment. These operators provide a shorthand way to update the value of a variable based on its current value. In this table, a
and b
represent variables or values that are being operated on.
Operator | Description | Example | Equivalent |
---|---|---|---|
+= | Add and assign | a += b | a = a + b |
-= | Subtract and assign | a -= b | a = a - b |
*= | Multiply and assign | a *= b | a = a * b |
/= | Divide and assign | a /= b | a = a / b |
%= | Modulus and assign | a %= b | a = a % b |
^= | Exponentiate and assign | a ^= b | a = a ^ b |
//= | Floor divide and assign | a //= b | a = a // b |
Miscellaneous Operators
Lua also provides other operators for specific operations and manipulations:
..
: Concatenation operator used to combine strings.#
: Length operator used to get the length of a string or table.
Concatenation Operator (..
)
The concatenation operator (..
) is used to combine strings in Lua. You can use this operator to concatenate two or more strings into a single string. Here's an example of using the concatenation operator in Lua:
local firstName = "Alice"
local lastName = "Smith"
local fullName = firstName .. " " .. lastName
print(fullName) --> "Alice Smith"
In this example, the strings firstName
and lastName
are concatenated to form the full name Alice Smith
.
Length Operator (#
)
The length operator (#
) is used to get the length of a string or table in Lua. For strings, the length operator returns the number of characters in the string. For tables, the length operator returns the number of elements in the table. Here's an example of using the length operator in Lua:
local text = "Hello, Lua!"
local length = #text
print(length) --> 11
In this example, the length operator #text
returns the number of characters in the string text
, which is 11
.
Operator Precedence
Operator precedence determines the order in which operators are evaluated in an expression. Operators with higher precedence are evaluated first. If operators have the same precedence, they are evaluated from left to right. You can use parentheses ()
to override the default precedence and explicitly specify the order of evaluation.
Here's the general order of precedence for Lua operators, from highest to lowest:
^
-
(unary),not
,#
*
,/
,%
+
,-
..
<
,<=
,>
,>=
==
,~=
and
or
By understanding operator precedence, you can write expressions that are clear, concise, and correctly evaluated in Lua.
Updated 4 months ago