table.len

local length = table.len(input)

--Regular table length
local t = {1, 2, 3, 4, 5}
local len = table.len(t)
engine.print(len) --5

--Packed table with n field
local packed = table.pack(1, nil, 3, nil, 5)
local len = table.len(packed)
engine.print(len) --5

--Table with holes (without n field)
local t = {1, 2, nil, 4}
local len = table.len(t)
engine.print(len) --4 (may vary, depends on #)

--Empty table
local t = {}
local len = table.len(t)
engine.print(len) --0

--Comparison with # operator
local t = {1, 2, 3}
engine.print(table.len(t)) --3
engine.print(#t) --3

--Packed table preserves correct length
local args = table.pack("a", nil, "b", nil, "c")
engine.print(#args) --May be incorrect with nil holes
engine.print(table.len(args)) --5 (always correct)

--Use in iteration
local t = table.pack(1, nil, 2, nil, 3)
for i = 1, table.len(t) do
    engine.print(i, t[i])
end

--Check if table is empty
local t = {}
if table.len(t) == 0 then
    engine.print("Table is empty")
end

--Mixed array and hash table
local t = {10, 20, 30, key = "value"}
local len = table.len(t)
engine.print(len) --3 (only counts array part)