Lua says they don't equal, but they do... wth?

[JonBoy2001]

So I've got some code here:

local HourCodeChanged = false
local Stored, Current
for i = 1, 8 do
	Stored = tonumber(ASDWeekHoursStored[name][i])
	Current = tonumber(ASDWeekHours[name][i])
	if Current ~= Stored then
		HourCodeChanged = true
		if (printit) then
			print(name.." iteration: "..tostring(i)..":"..Stored..":"..Current..":")
			print(type(Stored).." "..type(Current))
		end
	end
end
if (printit) then
	print(name.." HourCodeChanged "..tostring(HourCodeChanged))
end
return HourCodeChanged

Now, when printit is true, here's the results:

Solarhoof iteration: 1:9:9:
number number
Solarhoof HourCodeChanged true

For some god forsaken reason, it thinks 9 does not equal 9, and you'd think tonumber() would be a sure fire way to make sure I'm not comparing apples to oranges.

I'm at a loss here. I've been debugging this one little area for 4 hours now. The first few times this code is called, it's all ok, 9 equals 9. Then every time after that 9 does not equal 9. Reloading UI makes it work again for the first few times. It also doesn't bug out on the other 7 iterations. It's maddening!

[Deleted]

Is that an actual, full copy paste of your function? Or did you type it out for the forum/leave out anything?

[JonBoy2001]

This is the else section of an if statement for my function. Copy and pasted. Had to type out the print results though, the :s are there to make sure I didn't have some spaces or something.

---------- Post added 2012-09-08 at 09:36 PM ----------

As a side note, I've tried all sorts of things. Seeing what type my two variables were was the last straw

---------- Post added 2012-09-08 at 09:55 PM ----------

This is on the beta btw, and I have two WoW instances going at the same time for a raid. (this is a modified qdkp2) You don't think they'd be interfering with each other? That wouldn't make sense though, the variables are local and not savedvars....

[JonBoy2001]

Is it possible for a number that is actually 9.000000000001, or some other absurd long number of random 0's before the 1, to show up as a whole number when printed? After coding in some other areas and checking out the savedvars, I noticed some of this behaviour in other variables.

[Deleted]

You may be on to something here. It seems that between 13 and 14 zeros, the print() (and tostring(), too) function ignores them, but the comparison operator does not. As soon as 15 zeros, they both do (and the comparison shows them as equal again).

> local a = {"9."} for i=1,50 do a[i+1] = "0" a[i+2] = 1 local b = tonumber(table.concat(a,"")) print(i,b,tostring(b),b == 9) end
1       9.01    9.01    false
2       9.001   9.001   false
3       9.0001  9.0001  false
4       9.00001 9.00001 false
5       9.000001        9.000001        false
6       9.0000001       9.0000001       false
7       9.00000001      9.00000001      false
8       9.000000001     9.000000001     false
9       9.0000000001    9.0000000001    false
10      9.00000000001   9.00000000001   false
11      9.000000000001  9.000000000001  false
12      9.0000000000001 9.0000000000001 false
13      9       9       false
14      9       9       false
15      9       9       true
16      9       9       true
17      9       9       true
18      9       9       true
19      9       9       true
20      9       9       true
21      9       9       true
22      9       9       true
23      9       9       true
24      9       9       true
25      9       9       true
26      9       9       true
27      9       9       true
28      9       9       true
29      9       9       true
30      9       9       true
31      9       9       true
32      9       9       true
33      9       9       true
34      9       9       true
35      9       9       true
36      9       9       true
37      9       9       true
38      9       9       true
39      9       9       true
40      9       9       true
41      9       9       true
42      9       9       true
43      9       9       true
44      9       9       true
45      9       9       true
46      9       9       true
47      9       9       true
48      9       9       true
49      9       9       true
50      9       9       true

It seems that this behavior occurs for all arithmetic functions - even a multiplication by 100, for example, does not expose it. I'll try to figure out a way to work around this.

---------- Post added 2012-09-10 at 03:33 PM ----------

Upon further examination, this should solve the issue:

Stored = tonumber(tostring(ASDWeekHoursStored[name][i]))
Current = tonumber(tostring(ASDWeekHours[name][i]))

[JonBoy2001]

Ok, so I'm not crazy, lol. I'll have to sift through QDKP2s code and fix whatever is causing all these extra 0s. The numbers should only be in a ###.# format anyway. Since the comparison operator doesn't ignore it, could it be feasible to have a custom rounding function to round these to the first decimal? Only floor and ceil are available, right? Just in case I can't find the root cause and nip that in the bud, I like fixing root causes than using band-aids.

Thanks for the help man!

[Deleted]

local function round(number,digits)
    return tonumber(("%%.%df"):format(digits):format(number))
end

[JonBoy2001]

I am not worthy. I forgot about the string.format function.

I don't think the function name of round would be appropriate though. Maybe Stupid0Fix would suit it better.

Thanks Treeston!