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I am working on a little project, where the C code passes to Lua some parameters, then I build the basic architecture from it. The type of the passed value is lightuserdata as I see, and when I used print(tostring(id)) it wrote: userdata: <address>. I use this as a table field to store the built table. It works well, but I experience some strange thing. When I want to select a table, I use this:

function get(id) -- id is that lightuserdata that C core passes
	for a in pairs(t) do -- I store my tables in t
		if a == id then -- Checked, they are the same

No matter if I use return or t.a, the returning value is nil. After that I used return t[id], and strange, that works perfectly. Can somebody say me, what is the difference between . and []? Because the reference manual says: "The language supports this representation by providing as syntactic sugar for a["name"]. There are several convenient ways to create tables in Lua (see §2.5.7)."

Thanks: Attila