What are square brackets ([]) and hashtags (#) used for?
So while looking through morph scripts I found this:
01 | function onTouched(hit) |
02 | if hit.Parent:findFirstChild("Humanoid") ~= nil and hit.Parent:findFirstChild("Arm1") == nil then |
03 | local g = script.Parent.Parent.Arm1:clone() |
04 | g.Parent = hit.Parent |
05 | local C = g:GetChildren() |
06 | for i=1, #C do |
07 | if C[i].className == "Part" then |
08 | local W = Instance.new("Weld") |
09 | W.Part0 = g.Middle |
10 | W.Part1 = C[i] |
11 | local CJ = CFrame.new(g.Middle.Position) |
12 | local C0 = g.Middle.CFrame:inverse()*CJ |
13 | local C1 = C[i].CFrame:inverse()*CJ |
14 | W.C0 = C0 |
15 | W.C1 = C1 |
I'd like to know what the # (eg #C) and the square brackets (eg C[i]) mean. Thanks in advance!
2 answers
The Hashtag(#) symbol is used when referring to a quantity of something. i.e
1 | local aTable = {"Hello","Welcome","To","Scripting","Helpers!"} |
2 |
3 | for i = 1,#aTable do --The for loop executes depending on the number of items in aTable |
4 | print(aTable[i]) --This prints the string that corresponds with the item number; i.e. print(aTable[2]) would print, "Welcome" |
5 | end |
1 | --Output: |
2 | --Hello |
3 | --Welcome |
4 | --To |
5 | --Scripting |
6 | --Helpers! |
# is used to find the length of a list or a string. It returns a number.
[] are used to either search for a child via a string, or search a list via a number. It returns the object or value.
Brackets:
Just like a dot, but you can use a string, i.e.
1 | workspace.Part |
2 | -- = |
3 | workspace["Part"] |
Useful if then name of an object has spaces.
1 | --INCORRECT: |
2 | workspace.The Part |
3 |
4 | --CORRECT |
5 | workspace["The Part"] |
Can also be used to get a value from a table via a number;
1 | local myTable = {"valA", "valB", "valC"} |
2 | print(myTable[2]) --valB |
3 | print(myTable[3]) --valC |
4 | print(myTable[1]) --valA |
5 | print(myTable[math.random(1,3)]) --random |
If you have a variable for a number, and that variable is changing, you can "loop through" the list;
1 | local myTable = {"valA", "valB", "valC"} |
2 | for i = 1,3 do |
3 | print(myTable[i]) |
4 | end |
The GetChildren() method returns a table of all the children of an object, so it works the same way.
Number sign:
It's best not to think of it as a hashtag or the pounds symbol, because in Lua it is used as a number sign. When placed before a list, it return the number of that list. It can also be used for strings; it will return the number of characters.
1 | local myTable = {"valA", "valB", "valC"} |
2 | local myString = "Hello!" |
3 |
4 | print(#myTable) |
5 | print(#myString) |