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How and why did this 'for' loop get this many parts?

Asked by

TheeDeathCaster 2368

10 years ago

I was bored, so I decided to make a Part scanner script, and I did this test, instead of using + 1 for counting the parts, I tested + i and it printed out 183789, why and how did it get that many? o_e Here is the script;

local numParts = 0

local function partScan(part)
for i,v in pairs(part:GetChildren()) do
pcall(function() local testName = v.Name end)
if v:IsA("Part") then
numParts = numParts + i --This is the line that I used 'i' instead of '1'
end
partScan(v)
end
end

partScan(game.Workspace)
print(numParts)

1 answer

Answered by

Tkdriverx 514

10 years ago

Well, if you add i, you're adding the index of that specific table of children. Let's say the hierarchy looks like this (pretend it makes logical sense; the parenthesis and numbers is the number actually added to your variable):

Part (+1)
    Part (+1)
    Part (+2)
        Part (+1)
        Part (+2)
        Part (+3)
    Part (+3)
    Part (+4)
        Part (+1)
        Part (+2)
            Part (+1)
    Part (+5)

Basically doing your function is like doing this: 1 + 1 + 2 + 1 + 2 + 3 + 3 + 4 + 1 + 2 + 1 + 5, which equals 26, which clearly there are actually only 12.

Now, let's look at what happens if it doesn't find a "Part" like your code looks for, assuming this is the exact order it searches the children in:

Part (+1)
    Part (+1)
    Model -- Not a part, so it's not adding it.
    Part (+3)
        Part (+1)
        Part (+2)
        Model
        Part (+4)
    Part (+4)
    Part (+5)
        Part (+1)
        Model
        Part (+3)
            Model
            Part (+2)
    Part (+6)

Basically doing your function is like doing this: 1 + 1 + 3 + 1 + 2 + 4 + 4 + 5 + 1 + 3 + 2 + 6, which equals 33, which clearly there are actually 12 parts, still.

Conclusion: So, just stick with + 1 instead of + i to make a part counter to get the correct count.

Hint: If you want to get parts, use :isA("BasePart")instead of :isA("Part") because ALL types of bricks are BasePart.

So, its gathering a random amount of numbers from the Parts? TheeDeathCaster 2368 — 10y

It's not random. It depends all on how many children each item has inside it. Tkdriverx 514 — 10y

I hope this isn't too confusing. Tkdriverx 514 — 10y

Ah, I see, it's kind of like labeling them all, like in your explanation its doing 'Part #1' and 'Part #2', and its counting the numbers '#1' and '#2', is that right? I'm not too sure, so I'm making sure I'm atleast a bit onTrack. :P TheeDeathCaster 2368 — 10y

View all comments (8 more)

Yeah, that's the simple way of putting it. Except in tables, there are key-value pairs. Typically tables' key is a number, and it represents the location in the table numerically. Tkdriverx 514 — 10y

I have one more question, I've seen and used 'BasePart' before, but what does it do, or how does it work? TheeDeathCaster 2368 — 10y

BasePart is just the inherited class of all Bricks. Basically ALL bricks have the same properties of the BasePart class. http://wiki.roblox.com/index.php?title=API:Class/BasePart All these properties, methods, etc. are inherited down to all types of bricks. You may see some familiar ones. Tkdriverx 514 — 10y

So, it can tell that 'WedgePart' types are Parts too? :o TheeDeathCaster 2368 — 10y

Yes. WedgePart, SpawnLocation, Seat, Platform, FlagStand, Part, all are BaseParts, even Unions/NegateOperations. Tkdriverx 514 — 10y

Wow, you've been a big help man. :) I never knew all that before, I feel a bit silly now, haha! Thanks so much man. :) TheeDeathCaster 2368 — 10y

No problem. Tkdriverx 514 — 10y

One last thing: http://wiki.roblox.com/index.php?title=API:Class_Reference If you go here, you can see what is considered what. For example, if you look for BasePart, everything under that (and tabbed in) is considered a part of that specific class. As you can see here, EVERYTHING is under "Instance" as everything inherits the Instance properties. So if you use the :isA method on one of those clas Tkdriverx 514 — 10y

How and why did this 'for' loop get this many parts?

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