Strings and Math

Lua has built-in functions for working with text and numbers. Here are the ones you are likely to need for a HUD.

Converting values

tostring() turns a value into text. tonumber() tries to turn numeric text into a number:

lh.drawln("Visible: " .. tostring(true)) -- Output: Visible: true

local amount = tonumber("12.5")
lh.drawln(amount + 1) -- Output: 13.5

If conversion fails, tonumber() returns nil. Check before using the result:

local amount = tonumber("not a number")

if amount ~= nil then
    lh.drawln(amount * 2)
else
    lh.drawln("Please enter a number.")
end

Formatting text

string.format() fills placeholders in a string:

local fps = 120
local x = 12.345

lh.drawln(string.format("FPS: %d | X: %.1f", fps, x))
-- Output: FPS: 120 | X: 12.3

Placeholder	Meaning
%s	Text
%d	Integer
%.1f	Number with one decimal place
%.2f	Number with two decimal places
%%	A literal percent sign

Pass an integer to %d. Use a decimal format like %.1f for fractional values. Formatting changes the displayed text, not the original number.

Useful string functions

local text = "Hello, LuaHUD!"

lh.drawln(string.upper(text)) -- Output: HELLO, LUAHUD!
lh.drawln(string.lower(text)) -- Output: hello, luahud!
lh.drawln(string.sub(text, 1, 5)) -- Output: Hello
local start = string.find(text, "LuaHUD", 1, true)
lh.drawln(start) -- Output: 8

string.sub() includes both endpoints. string.find() returns the start and end positions, or nil if the text is missing. Assigning it to one variable keeps only the first result. Its fourth argument, true, makes it search for literal text instead of a Lua pattern.

These positions count bytes, so avoid cutting through characters that use multiple bytes.

Useful math functions

Expression	Result	Meaning
math.floor(12.8)	12	Round down
math.ceil(12.2)	13	Round up
math.abs(-5)	5	Absolute value
math.min(10, 20)	10	Smaller value
math.max(10, 20)	20	Larger value

Rounding down goes toward negative infinity: math.floor(-1.2) is -2.

To keep a number inside a range, combine min and max:

local percentage = 125
percentage = math.max(0, math.min(100, percentage))
lh.drawln(percentage) -- Output: 100