You would do:
for i,v in pairs(game.Players:GetChildren()) do
-- v is your player
end
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You can use pairs to run through a table. The Players service has a method called GetPlayers(), which returns an unsorted list of all players in the game.
You can iterate through them like so:
local Players = game:GetService("Players") -- you should use GetService over game.Players!
for _, player in pairs(Players:GetPlayers()) do
-- this code will run for all players
end
Note that if the loop is broken, returned, or an error occurs the loop will stop.
You should always have helpful variable names, and not use unneeded variables.
for i,v in pairs(array) do
-- we may not need i here
-- besides, what is v meant to be??
end
Your code should always be optimized for reading!!
5 Likes
You should use ipairs over pairs. GetPlayers returns an array, ipairs runs quicker and it’s idiomatic for contiguous arrays. pairs is designed more for a dictionary where your keys aren’t known (noting that it returns next).
Use cases aside, it’s also good for collaborators and being clear as to what part of the table you’re intending to traverse through. I know when I see ipairs I understand that an array is being iterated over.
7 Likes
Well it’s a good idea, might work but in all honesty it’s not quite efficient (very inefficient).
@ElliottLMz Firstly I don’t see the need to index all players , on top of unnecessarily iterating through them in key, value pairs. It would take significantly less time returning values through index, value pairs, that is in ipairs, which I recommend you to use over in pairs for this case.
@TheWorstOne_2
Here’s a sample of what you would do to print players’ names , by iterating through an array of players :
local Players = game:GetService("Players")
Players.PlayerAdded:Connect(function()--each time a player is added
--// Loop through all existing players and..print everyone's name
for _, player in ipairs(Players:GetPlayers()) do
print("Player name : ".. player.Name)
end
end)
However if you would want to not print everyone’s name each time a player joins, you could save the player’s names in table to prevent duplicate prints, like :
local Players = game:GetService("Players")
Current_Players = {}--we will save player's names here
Players.PlayerAdded:Connect(function()--each time a player is added
--// Loop
for _, player in ipairs(Players:GetPlayers()) do
if Current_Players[player.Name] then--if he is already in the table then
return--or you could do if table.find(Current_Players,player.Name) etc.
end
table.insert(Current_Players,player.Name)
print(player.Name.. " has joined the game")
end
end)
@ElliottLMz
what do you mean?
v here would be the player, it’s necessary,
also using pairs here is a terrible idea as we don’t actually need to go through key value pairs, as @PostApproval already mentioned something similar , your code would also not work at all, unless you connect the loop to an event , that runs after players actually exist in the game. (like players.PlayerAdded)
2 Likes
I was honestly just answering the question on how to loop through all players quickly and not trying to give the most efficient way (I should have)
1 Like
What does “idiomatic for contiguous arrays” mean? I’m not quite understanding the advantage ipairs has over pairs.
It’s easy to just pick pairs to iterate over any table but that often is a product of not understanding ipairs or what’s going on behind a for loop.
ipairs is designed to iterate over the array part of a table at an incremental level (index i+1 per iteration). ipairs will also guarantee ordered iteration and terminate at the first hole in an array. ipairs also makes it clear that what you’re iterating over is an array.
pairs, on the other hand, is designed to iterate over the hash part of a table. pairs is slightly slower because the keys aren’t known to the generator at the start, so it calls next to find which key-value pair should be iterated over next.
LuaU optimisations sped both generators up by a large amount, however ipairs saw the greater increase as noted by some benchmarks at RDC 2019 for the Lua As Fast As Possible presentation.
2 Likes
Using pairs, the iterator function is the next function, meaning if a value isn’t found for each key then it would return nil rather than stop the loop.
Ipairs on the other hand, iterates through index value pairs rather than key value pairs, and if nil is encountered through 1 to #t then the loop would stop.
Using Index value pairs (in ipairs ) also requires lesser time as no value is associated with keys, for example :
for i = 1 ,#t
print ( t[i] )
Use ipairs where speed matters, and key value association is unnecessary.
Slightly unrelated: but is ipairs a recent thing? I’ve seen older scripts do:
local fruits = {"Apple", "Pear", "Pineapple", "Grapes"}
for i=1, #fruits do
local fruit = fruits[i]
end
Was this to keep code fast before ipairs?
ipairs is not recent, it has existed since old versions of Lua (so for years). A numeric for loop was more common to use before LuaU optimisations because for whatever reason, Roblox’s implementation of ipairs was reported as noticeably slow enough not to use it. ipairs now sits as the fastest generator.
Will recomend you to use for i,v in pairs
FX. for i,v in pairs(game.Players:GetChildren()) do
i: is how many times the loop has looped and v: is the players
Hope that makes sense
As afforementioned, that is an inefficient method. Moreover, this topic is already solved.
-
iandvare unclear - You should be using
GetService -
ipairsis more efficient for arrays
1 Like
's not how pairs works. i, v is a key-value pair of an associative array and pairs specifically traverses through the hash part of a table implementing next to search for the next pair.
1 Like
There is 2 ways to use for i,v in pairs u can do
local fruits = {“Apple”, “Pear”, “Pineapple”, “Grapes”
for i=1, #fruits do
local fruit = fruits[i]
print(fruit)
end
or just do what i just said
Those are different and the one you just posted does not implement pairs. Pairs is a generator for a generic for loop, what you wrote is a numeric for loop. Numeric for loops deal in incremental indices and lookups only. You have an array so use ipairs. Scroll up for more information.
Reading material on for loops:
Programming in Lua : 4.3.4 - Numeric for
Programming in Lua : 4.3.5 - Generic for
2 Likes
Ohhh, well thx for the help i didn’t know that
Hello, I’m sort of new In scripting, May I ask why sometimes in “for” you need to have “`i, v” what both of the characters stand for? Thanks for the solution tho.
The first value in this case is index, how many times you’ve looped so far. V is the value of the list.
You need them because it’s for _,v in pairs, which is why there’s two values, it’s a pair.
Also you shouldn’t necrobump, especially 3 years later. There’s plenty of explanations out there for that.
Thank you very much, I just thought that it would be easier to ask it here Because I’ve tried to find some info about it and didn’t find any. I’m trying to learn scripting in these times. 
1 Like