Operators

Lua comes with numerous built-in operators.

Arithmetic operators

Arithmetic operators like +, -,*,/ are applied to numbers. Since numbers are floating point numbers in Lua, divisions are always floating point divisions:

1.0 / 2   -- result 0.5
1 / 2     -- result 0.5, not 0
1 - 3*4   -- result -11
41/10     -- result 4.1

Assignment operator

The assignment operator = overwrites the variable at the left-hand side with the result of the right-hand side operation.

i = 10 - 2  -- result i==8

Operator . .

The .. operator concatenates data to character strings (after converting them to strings).

"At receiver: " .. 10.3 .. " dB" 
-- result: "At receiver: 10.3 dB"

Comparison operators

Comparison operators compare values. They always evaluate to true or false.

1 == 1 -- result: `true`
2 == 1 -- result: `false`
2 <= 1 -- result: `false`
2 >  1 -- result: `true`
2 >= 1 -- result: `true`
2 ~= 1 -- inequality, result: `false`
-- etc

Logical operators

Logical operators and, or and not can express logical statements. They operate on boolean values and show the following behavior:

not true -- result: `false`
not false -- result: `true`
false and x -- result: `false` (short-circuit)
true and x -- result: `x` 
false or x -- result: `x`
true or x -- result: `true` (short-circuit)

and, or and not can be used with non-boolean values as well. Lua interprets nil as if it was false and all other values as true-equivalent.

not 0 -- result: `false` since 0 is true-ish
not nil -- result: `true` since nil is false-ish