string.len

local length = string.len(input)

--Get length of string
local len = string.len("hello")
engine.print(len) --5

--Empty string
local len = string.len("")
engine.print(len) --0

--String with spaces
local len = string.len("hello world")
engine.print(len) --11

--String with special characters
local len = string.len("hello\nworld")
engine.print(len) --11

--String with null byte
local len = string.len("hello\0world")
engine.print(len) --11

--Numbers as strings
local len = string.len("12345")
engine.print(len) --5

--Using # operator (alternative)
local len = #"hello"
engine.print(len) --5

--Comparing both methods
local str = "Lua programming"
engine.print(string.len(str)) --15
engine.print(#str) --15
engine.print(string.len(len)) --15

--Multi-byte UTF-8 characters count as multiple bytes
local str = "hello™"
engine.print(string.len(str)) --8

--Use in conditionals
if string.len("test") > 0 then
    engine.print("String is not empty")
end

--Get length before and after trimming
local str = "  hello  "
engine.print(string.len(str)) --9

local trimmed = string.gsub(str, "^%s+", "")
trimmed = string.gsub(trimmed, "%s+$", "")
engine.print(string.len(trimmed)) --5