Re: table.maxn...

[Roberto Ierusalimschy <roberto@...>]

> On Mon, Jun 1, 2015 at 6:26 AM, Coda Highland <chighland@gmail.com> wrote:
> > On Mon, Jun 1, 2015 at 3:06 AM, Tim Hill <drtimhill@gmail.com> wrote:
> >> This also takes care
> >> of the issue of FP errors, since all the math is now done on integers.
> 
> Also, it doesn't resolve FP errors in Lua 5.1/5.2, because numbers are
> still double-precision floats and not true integers. The act of adding
> 1 + 1<<53 is what causes the problem, not dealing with fractional
> values.

I use the following code (or rather I would use it if ever I had to
check whether a table is a sequence :-):

function issequence (t)
  local n = #t
  local c = 0   -- count keys in [1..n]
  for k in pairs(t) do
    if type(k) == 'number' and k > 0 then
      if k ~= math.floor(k) or k > n then return false end
      c = c + 1
    end
  end
  return c == n
end


-- Roberto