Does a ‘return’ statement restart a ‘while true do’? I’ve looked it up and still don’t understand what it does.
65 Likes
return is the keyword you use to return a value. such as this:
local function Multiply(a,b)
return a*b
end
local value = Multiply(2,4) -- multiply 2 by 4.
print(value) -- 8
edit: @forkmeongithub beat me to it
46 Likes
So how would I restart a while true do statement after it breaks?
1 Like
You can put it in a function, and call the function whenever you need the loop to run again.
For example:
function Add(n1, n2)
return n1+n2
end
print("2 plus 2 is " .. Add(2,2))
wait(3)
print("Let's call the function again! Hm, what is 4 plus 4 equal to? Oh right, it's " .. Add(4,4))
17 Likes
For the loop to work it requires a player variable. The loop is to make a pet follow the player.
Here’s the script:
equipPetEvent.OnServerEvent:Connect(function(player, item)
local equippedPetFolder = player:WaitForChild("EquippedPet")
local equippedPet = equippedPetFolder:GetChildren()
local char = player.Character
local hum = char.Humanoid
local torso = char.UpperTorso
local maxFloat = 1
local floatInc = 0.025
local sw = false
local fl = 0
for i,v in pairs(equippedPet) do
v:Destroy()
end
item:Clone().Parent = equippedPetFolder
local charChildren = char:GetChildren()
for i,y in pairs(charChildren) do
if y:FindFirstChild("Pet") then
y:Destroy()
end
end
local petInChar = item:Clone()
petInChar.Parent = char
local pet = petInChar.Part
confirmEquipPetEvent:FireClient(player)
while true do
wait()
if char:FindFirstChild(item.Name) then
if not sw then
fl = fl + floatInc
if fl >= maxFloat then
sw = true
end
else
fl = fl - floatInc
if fl <=-maxFloat then
sw = false
end
end
if pet ~= nil and hum ~= nil and torso ~= nil then
if hum.Health > 0 then
local cf = torso.CFrame * CFrame.new(3,2+fl,3)
pet.BodyPosition.Position = Vector3.new(cf.x,cf.y,cf.z)
pet.BodyGyro.CFrame = torso.CFrame * CFrame.new(3,0,-3)
else
char[item.Name]:Destroy()
if not char:FindFirstChild(petInChar.Name) then
print("Dead")
wait(6.5)
workspace:WaitForChild(player.Name)
print("Player respawned")
local newPet = item:Clone()
newPet.Parent = player.Character
end
end
end
end
end
end)
4 Likes
It would help if you could post what the aim here is, perhaps after we know that we can propose a better solution or suggest a method you can use to accomplish your goal. Right now all we know is that you want to know the behavior of ‘return’ in a while loop. A while loop will stop when the condition is no longer met.
3 Likes
You mean this?
3 Likes
yes, I want the loop to stop when the player dies. Then respawn the pet and carry on the loop.
‘item’ is the pet
2 Likes
You could use repeat rather than while for this. The script will repeat something until the condition specified is met. In this case you could do:
repeat
-- Pet following character code here
until not Player.Character -- (Or until player humanoid is dead, etc)
Also this thread is now derailing completely from the original question, and is completely unrelated. In the future before posting in this category read these guidelines.
7 Likes
Example from real life:
You go to a restaurant and order a sandwich and a drink. A bit later, you receive the sandwich and drink. In other words, you gave the restaurant input (your order) and it in turn gave an output (sandwich and drink).
The process of the restaurant outputting would be what return does. In this analogy, you are the caller of the function, and the restaurant is the function.
function Restaurant:OrderFood(orderInfo)
-- Do some stuff to figure out the actual food
return food
end
-- You, the customer:
local myFood = Restaurant:OrderFood("Sandwich", "Water")
60 Likes
In general terms, return outputs anything from a scope depending on the input after return.
function test_a()
return "hi"
end
function test_b(number)
return number + 2
end
function test_c()
return workspace:FindFirstChild("foo") -- let's say there was a part in the workspace named "foo"
end
print(test_a()) -- > hi
print(test_b()) -- > your input number in parameter + 2
print(test_c().Name) -- > foo
Simplification: return = output from a scope(if statements, functions, loops(it’ll break the loop))
7 Likes
This could be slightly misleading, I think. A break statement will exit the current scope (if-then, loop, etc) but a return statement will end the currently-executing function and return control to the caller no matter how many levels of loops or conditionals it’s inside. In other words, you can’t use return to jump out of just one level of nested loops, that is what break is for. In Roblox scripts, a return statement that’s not inside a function will terminate the script. In the case of a ModuleScript, the contents of the module is essentially a function, and you normally return something useful, like a table built by the module, or reference to a function within it.
11 Likes
Can also be used organizationally and to end a function prematurely -
function checkobjectsize(object)
if not object:IsA("BasePart") then return end
return "Size = "..tostring(object.Size)
end
print(checkobjectsize(game.Workspace.Part))
Will print either nil or the Object’s size and looks better than:
function checkobjectsize(object)
if object:IsA("BasePart") then
return "Size = "..tostring(object.Size)
end
end
3 Likes
At a lower level, returns and breaks are very different. Your Lua code is compiled into a form of byte code similar to machine code that your processor uses. When your script runs, the Lua interpreter reads your byte code like a CPU would read machine code. The Lua interpreter is compiled to machine code and when it reads a byte code from your script, it tells the CPU to execute a section of machine code in the interpreter that effectively performs what the byte code instructed to do. Thus, Lua is called a an interpreted language because it never actually runs directly on the hardware but it describes what needs to be done. The interpreter normally works by reading straight down the bytecode list of instructions that make up your script, one per a “line”. When you use “return”, “break”, “if”, “for”, “while”, or “repeat” then you alter the order in which the interpreter reads your script.
When return and break are translated into byte code, they become into two completely different instructions. Return has its own instruction (just like in x86 machine code / assembly) while break uses the JMP instruction (which has a similar x86 instruction as well).
JMP is a simple instruction that tells the Lua interpreter which instruction to execute next. A JMP instruction tells it to stop reading and start again at a different line.
A RET instruction is a slightly more complex instruction that tells the Lua interpreter to return to the last bookmark. For it to function properly, a bookmark needs to be set using the CALL instruction. To explain how these work, assume that the interpreter is chugging along reading and executing byte code until it reaches a CALL instruction. When it does, it works similarly to a JMP instruction. It stops reading where it was and starts reading where CALL tells it to. While there are more differences, the most important one is that it leaves a bookmark to remember where it was. Depending on how many CALL instructions are encountered, we could have many bookmarks at once. These are stored on what is referred to as “the stack”. The stack functions like a stack of plates at a restaurant: the first plate on the stack is that last plate to be taken off. In similar fashion, a RET instruction tells the interpreter to stop reading where it is and resume reading at the last bookmark on the stack.
Now to make these ideas more concrete. Each function in your code is turned into a single list of instructions. JMP instructions make if statements, loops, and similar language features change which instructions the interpreter reads even though all of the code is just a long list of instructions. A break statement breaks the last loop it was found in by performing a JMP to the first instruction after it. A return statement returns from the function entirely and resumes execution of the code that called it. Here are some examples:
local function foo()
print '2'
-- even if you don't put a 'return',
-- Lua always returns at the end of a function
end
print '1'
foo()
print '3'
This code will print 1, 2, and 3 on different lines in that order. When foo is called, a bookmark is made. When the end of foo is reached, execution returns to that bookmark.
print '1'
for i = 1, 10 do
print(i)
if i == 5 then
break
end
end
print '11'
This code will print 1, 2, 3, 4, 5, and 11 on different lines in that order. After each print, Lua checks if i == 5. If it is, then it JMPs to the first instruction after the loop, the print '11'. Otherwise, it continues down the list of instruction. In a for loop, it checks if ‘i ~= 10’ at the end. If it doesn’t, then it JMPs back to the beginning of the loop, otherwise allowing the interpreter to fall through to the print '11' statement.
17 Likes
Think of someone throwing you a ball, and asking for it back - so you return the ball.
The same applies in programming, typically relating to math.
If you have used Microsoft Excel before, you’ll understand that when you type in something like;
=SUM(1,2)
it adds 1 and 2 together - returning 3 in the cell.
We can do the exact same with programs
a = 1
b = 2
print(a + b)
--prints out 3
Different types of values can be returned:
- Numbers
- Boolean (true/false)
- Strings (text)
- Tables (lists)
- Objects (posts, models, etc)
In some programming languages, such as C#, you have to define what type of value you want to return.
However Lua is much simpler as it let’s you return whatever you want from a function.
function add(a, b)
return a + b -- tell the function to stop here and return the sum of a and b
end
print(add(1, 2))
-- prints out 3
local newValue = add(2, 3) -- 5
local anotherValue = add(1, add(2,3) ) -- 6
Have fun.
7 Likes
I feel like this is an XY problem. It’d be better to ask about the actual problem, which seems to be getting your game’s “pets” to float near players and how your current code is faulty, over obscure questions such as “how do you restart a while loop” or “what does return do” (since they’re all unrelated and 3 different questions).
Return can be used as an expression to exit out of the scope or return a value in a callback.
While loops run until their condition is met or the loop is broken. You can’t restart a while loop unless you have something to create it (i.e. a function).
local function SpawnSomeWhileLoop()
while condition do
-- stuff
end
-- Nothing here runs until the above stops
end
SpawnSomeWhileLoop()
-- Nothing below here runs unless you put the call in a spawn or coroutine
As for your code, I think you’re looking for a different solution. As it is, your code possesses its own respective flaws:
- There seem to be no server-side checks on the remote, so exploited clients can leverage this remote by passing anything in the “item” argument for use by the server
- You might want to consider a module or external script that appends logic to the pet, rather than relying on the remote’s connected function to do it
- The remote should only handle the equipping part of things. An external script or module should be the actual code that acts to give pets their code logic (i.e. floating).
1 Like
You could try coroutines for this. Break and return keywords stop a loop in its tracks, but coroutines have the sort of behavior you want.
When you yield a coroutine it will stop the entire thread/loop, but when you resume it, it will start the function all over again. I recommend going to the roblox wiki to understand the API.
1 Like
Return returns a value when called in a function.
Whenever called it will immediately stop the function and return the given value.
If I’m correct, whenever return is used in a loop it should also stop the loop like break.
function returnstuff(a, b)
return a + b
end
print(returnstuff(2, 2)) --4
local continue = false
function dostuff()
print("Start.")
if not continue then return end --Function will stop here if continue is false.
print("Function continued.") --This will never happen because return stops the function.
print("End.")
end
dostuff()
function loopthingy()
print("Start.")
for x = 1, 10 do
print(x)
if x == 5 then return x end --Will stop the x loop halfway.
end
print("End.") --Will never print because return was used inside the loop.
end
print(loopthingy()) --5
Not the best example but maybe this gives a idea of how it works.
4 Likes
When running a while true do loop when you do return it iterates over again.
Edit: I meant if you just simply put ‘return’ with no arguments, I think it works that way judging from my experience.
1 Like