How to get number of entries in a Lua table?

lua

Solution

You already have the solution in the question -- the only way is to iterate the whole table with `pairs(..)`.

function tablelength(T)
  local count = 0
  for _ in pairs(T) do count = count + 1 end
  return count
end

Also, notice that the "#" operator's definition is a bit more complicated than that. Let me illustrate that by taking this table:

t = {1,2,3}
t[5] = 1
t[9] = 1

According to the manual, any of 3, 5 and 9 are valid results for `#t`. The only sane way to use it is with arrays of one contiguous part without nil values.

Problem

Sounds like a "let me google it for you" question, but somehow I can't find an answer. The Lua `#` operator only counts entries with integer keys, and so does `table.getn`: ``` tbl = {} tbl["test"] = 47 tbl[1] = 48 print(#tbl, table.getn(tbl)) -- prints "1 1" count = 0 for _ in pairs(tbl) do count = count + 1 end print(count) -- prints "2" ``` How do I get the number of all entries without counting them?

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