Operators

An operator is a symbol that tells the interpreter to perform specific mathematical or logical manipulations. Lua language is rich in built-in operators and provides the following type of operators −

This tutorial will explain the arithmetic, relational, logical, and other miscellaneous operators one by one.

Arithmetic

A = 10, B = 20

+ Adds two operands A + B will give 30
- Subtracts second operand from the first A - B will give -10
* Multiply both operands A * B will give 200
/ Divide numerator by de-numerator B / A will give 2
% Modulus Operator by an integer division B % A will give 0
^ Exponent Operator takes the exponents A^2 will give 100
- Unary - operator acts as negation -A will give -10

Relational

== Checks two operands are equal or not, if yes then condition becomes true.
~= Checks two operands are equal or not, if values are not equal then condition becomes true.
> Checks left operand is greater than the value of right operand, if yes then condition becomes true.
< Checks left operand is less than the value of right operand, if yes then condition becomes true.
>= Checks left operand is greater than or equal to the value of right operand, if yes then condition becomes true.
<= Checks left operand is less than or equal to the value of right operand, if yes then condition becomes true.

Example

(A == B) is not true. (A ~= B) is true. (A > B) is not true. (A < B) is true. (A >= B) is not true. (A <= B) is true.

Logical

and Called Logical AND operator. If both the operands are non zero then condition becomes true.
or Called Logical OR Operator. If any of the two operands is non zero then condition becomes true.
not Called Logical NOT Operator. Use to reverses the logical state of its operand. If a condition is true then Logical NOT operator will make false.

Misc

Miscellaneous operators supported by Lua Language include concatenation and length.

.. Concatenates two strings.

a..b where a is “Hello “ and b is “World”, will return “Hello World”.

# An unary operator that return the length of the a string or a table.

#"Hello" will return 5

Operators Precedence

Operator precedence determines the grouping of terms in an expression. This affects how an expression is evaluated. Certain operators have higher precedence than others.

Here, operators with the highest precedence appear at the top of the table, those with the lowest appear at the bottom. Within an expression, higher precedence operators will be evaluated first.

Unary not # - Right to left
Concatenation .. Right to left
Multiplicative * / % Left to right
Additive + - Left to right
Relational < > <= >= == ~= Left to right
Equality == ~= Left to right
Logical AND and Left to right
Logical OR or Left to right