Lua - changing 'stop' variable's value from within the for-loop, will it terminate as normal still?

Question

For example, if I do the following:

local iStop = 32
for i = 1, iStop do
  iStop = iStop + 1
end

Will the loop be guaranteed to run only 32 iterations, or is there any case it may run infinitely?

Answer 1

Please refer to the Lua Reference Manual 3.3.5: For statement

 for v = e1, e2, e3 do block end

is equivalent to the code:

 do
   local var, limit, step = tonumber(e1), tonumber(e2), tonumber(e3)
   if not (var and limit and step) then error() end
   var = var - step
   while true do
     var = var + step
     if (step >= 0 and var > limit) or (step < 0 and var < limit) then
       break
     end
     local v = var
     block
   end
 end

...

All three control expressions are evaluated only once, before the loop starts.

The loop will run 32 times. The actual loop limit is a copy of iStop's value befor the loop starts and no matter what you do to iStop in the loop it will not affect the loop limit.